To get started using the library, you need to make sure that the library
and dependencies can be imported. Short instructions:

sudo python setup.py install

or

python setup.py install --home=~
and set your PYTHONPATH to include your home directory.

Long instructions copied from the following article from Aug. 2007:

Getting Started with the Google Data Python Library 
http://code.google.com/support/bin/answer.py?answer=75582

==Introduction==

So you've decided to use the Google data Python client library to write an 
application using one of the many Google data services. Excellent choice! 
My aim with this short tutorial is to quickly get you started in using the
client library to develop your application.

You probably want to jump in and start creating your application right 
away. First though, you may need to configure your development environment 
and set up the tools you'll need to run the modules included in the client
library. Follow the steps below and you'll be running code in no time.

==Installing Python==

If you're going to be developing with the Python client library, you'll 
need a working version of Python 2.2 or higher. Many operating systems
come with a version of Python included, so you may be able to skip the 
installation step. To see which version of Python you have, run 
python -V in a command line terminal. (Note: the V is uppercase.) This
should result in something like:

Python 2.4.3

If you see version 2.2 or higher, then you can start installing dependencies.
Otherwise, look below to find installation/upgrade instructions for your 
operating system.

--Installing Python on Windows--

There are quite a few implementations of Python to choose from in Windows,
but for purposes of this guide, I'll be using the .msi installer found on 
python.org.

   1. Begin by downloading the installer from the Python download page. 
      http://www.python.org/download/
   2. Run the installer ? you can accept all the default settings
   3. To see if your install is working as expected, open a command prompt and
      run python -V.

--Installing Python on Mac OS X--

The list of downloads on python.org has .dmg installers for the Mac users out
there. Here are the steps to install one of them:

   1. Navigate to http://www.python.org/download/mac/
   2. From this page, download the installer for the appropriate version of 
      Mac OS X. Note: The Python installation page for Mac OS X 10.3.8 and 
      below is different than newer versions of Mac OS X. To find your OS X
      version, choose About This Mac from the Apple menu in the top-left 
      corner of your screen.
   3. After the download finishes, double-click the new disk image file
      (ex. python-2.5-macosx.dmg) to mount it. If you're running Safari, this
      has already been done for you.
   4. Open the mounted image and double-click the installer package inside.
   5. Follow the installation instructions and read the information and 
      license agreements as they're presented to you. Again, the default 
      settings will work fine here.
   6. Verify the installation by opening Terminal.app 
      (in /Applications/Utilities) and running python -V. The installation's
      version should appear.

--Installing Python on Linux--

To install on Linux and other *nix style operating systems, I prefer to
download the source code and compile it. However, you may be able to use your
favorite package manager to install Python. (For example, on Ubuntu this can
be as easy as running sudo apt-get install python on the command line.) To
install from source, follow these steps:

   1. Download the source tarball from the Python download page.
      http://python.org/download/
   2. Once you've downloaded the package, unpack it using the command line.
      You can use the following

      tar zxvf Python-2.<Your version>.tgz

   3. Next, you'll need to compile and install the source code for the Python
      interpreter. In the decompressed directory, run ./configure to generate
      a makefile.
   4. Then, run make. This will create a working Python executable file in 
      the local directory. If you don't have root permission or you just want
      to use Python from your home directory, you can stop here. You'll be 
      able to run Python from this directory, so you might want to add it to
      your PATH environment variable.
   5. I prefer to have Python installed in /usr/bin/ where most Python 
      scripts look for the interpreter. If you have root access, then run 
      make install as root. This will install Python in the default location
      and it will be usable by everyone on your machine.
   6. Check to see if your install is working as expected by opening a 
      terminal and running python -V.

==Installing Dependencies==

Currently, the only external dependency is an XML library named ElementTree.
If you are using Python version 2.5 or higher, you won't need to install 
ElementTree since it comes with the Python package.

To see if ElementTree is already present on your system, do the following:

   1. Run the Python interpreter. I usually do this by executing python on
      the command line.
   2. Try importing the ElementTree module. If you are using Python 2.5 or
      higher, enter the following in the interpreter:

      from xml.etree import ElementTree

      For older versions, enter:

      from elementtree import ElementTree

   3. If the import fails, then you will need to continue reading this 
      section. If it works, then you can skip to Installing the Google 
      data library.
   4. Download a version which is appropriate for your operating system.
      For example, if you are using Windows, download 
      elementtree-1.2.6-20050316.win32.exe. For other operating systems,
      I recommend downloading a compressed version.
   5. If you are using a .tar.gz or .zip version of the library, first
      unpack, then install it by running ./setup.py install.

Running ./setup.py install attempts to compile the library and place it in
the system directory for your Python modules. If you do not have root access,
you can install the modules in your home directory or an alternate location by
running ./setup.py install --home=~. This will place the code in your home 
directory.

There is another option which avoids installing altogether. Once you 
decompress the download, you will find a directory named elementtree. This
directory contains the modules which you will need to import. When you call
import from within Python, it looks for a module with the desired name in 
several places. The first place it looks is in the current directory, so 
if you are always running your code from one directory, you could just put
the elementtree directory there. Python will also look at the directories
listed in your PYTHONPATH environment variable. For instructions on 
editing your PYTHONPATH, see the Appendix at the end of this article. 
I recommend using ./setup.py install for elementtree.

==Installing the Google Data Library==

Download the Google data Python library if you haven't done so. Look for the
latest version on the Python project's downloads page.

After downloading the library, unpack it using unzip or tar zxvf depending
on the type of download you chose.

Now you are ready to install the library modules so that they can be imported
into Python. There are several ways you can do this:

    * If you have the ability to install packages for all users to access, 
      you can run ./setup.py install from the unpacked archive's main 
      directory.
    * If you want to install these modules for use in your home directory,
      you can run ./setup.py install --home=<your home directory>.

In some cases, you want to avoid installing the modules altogether. To do 
that, modify your PYTHONPATH environment variable to include a directory
which contains the gdata and atom directories for the Google data Python
client library. For instructions on modifying your PYTHONPATH, see the 
Appendix at the end of this article.

    * One final option that I'll mention, is copying the gdata and atom
      directories from the src directory into whatever directory you are
      in when you execute python. Python will look in the current directory
      when you do an import, but I don't recommend this method unless you 
      are creating something quick and simple.

Once you've installed the Google data library, you're ready to take the
library for a test drive.

==Running Tests and Samples==

The Google data Python client library distributions include some test cases
which are used in the development of the library. They can also serve as a
quick check to make sure that your dependencies and library installation are
working. From the top level directory where you've unpacked your copy of the
library, try running:

./tests/run_data_tests.py

If this script runs correctly, you should see output on the command line 
like this:

Running all tests in module gdata_test
.......
----------------------------------------------------------------------
Ran 7 tests in 0.025s

OK

Running all tests in module atom_test
..........................................
----------------------------------------------------------------------
Ran 42 tests in 0.016s

OK

...

If you did not see any errors as the tests execute, then you have probably set
up your environment correctly. Congratulations!

For further information see the original article: 
http://code.google.com/support/bin/answer.py?answer=75582

==Appendix: Modifying the PYTHONPATH==

When you import a package or module in Python, the interpreter looks for the
file in a series of locations including all of the directories listed in the
PYTHONPATH environment variable. I often modify my PYTHONPATH to point to 
modules where I have copied the source code for a library I am using. This 
prevents the need to install a module each time it is modified because 
Python will load the module directly from directory which contains the 
modified source code.

I recommend the PYTHONPATH approach if you are making changes to the client
library code, or if you do not have admin rights on your system. By editing
the PYTHONPATH, you can put the required modules anywhere you like.

I modified my PYTHONPATH on a *nix and Mac OS X system by setting it in my 
.bashrc shell configuration file. If you are using the bash shell, you can 
set the variable by adding the following line to your ~/.bashrc file.

export PYTHONPATH=$PYTHONPATH:/home/<my_username>/svn/gdata-python-client/src

You can then apply these changes to your current shell session by executing 

source ~/.bashrc.

For Windows XP, pull up the Environment Variables for your profile: 
Control Panel > System Properties > Advanced > Environment Variables. From 
there, you can either create or edit the PYTHONPATH variable and add the
location of your local library copy.