If you only want to use clan, install it this way:
pip install clan
clan is intended for researchers and analysts. You will need to understand the Google Analytics API in order to use it effectively. It is not intended to generate reports for your boss.
If you are a developer that also wants to hack on clan, install it this way:
git clone git://github.com/onyxfish/clan.git cd clan mkvirtualenv --no-site-packages clan pip install -r requirements.txt python setup.py develop
If you have a recent version of pip, you may need to run pip with the additional arguments --allow-external argparse.