You're a SourceForge/Snitz developer if you have a developer account on the sf2k project at SourceForge. If you don't have an account there, you still can be a development team member at the Snitz support site at http://forum.snitz.com/, those two accounts are not linked.
First thing you need to do is to read the installation chapter. It explains what to install and how to install that.
After that, you need to create a new repository and checkout the existing code on the site. How you do that is explained in the basic functions chapter.
Even if you do not have a developer account, CVS can be usefull to you. You need a bit less software and setup though.
tbd.....