Create a github account at http://github.com. Once you've got your account set up let me know what your handle is so I can give you access to the topratedpump file repository.
Follow the steps for Mac OS X on this page: http://github.com/guides/providing-your-ssh-key Once you get your SSH key set up you'll need to visit your github account page and paste in your key there: https://github.com/account
Download and install MacPorts from http://www.macports.org/
Open up Terminal.app (Use spotlight or quicksilver to find it) and type the following things..
port install git-core (this will take a while and might prompt you a few times)