We highly recommend using virtualenv and virtualenvwrapper to work on RapidSMS. These tools provide isolated Python environments, which are more practical than installing packages system wide. They also allow installing packages without administrator privileges.
sudo pip install --upgrade virtualenv
sudo pip install --upgrade virtualenvwrapper
Then follow the virtualenvwrapper install docs to setup your shell properly.
mkvirtualenv --distribute --no-site-packages rapidsms
workon rapidsms