I've found an article on developer.apple.com, with step-by-step instructions on enabling and using CVS (Concurrent Versioning System) on OS X.
If you use CVS and need a GUI for the UNIX environment, consider using CVL (Concurrent Versions Librarian), a free Cococa configuration management tool for CVS.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20031212134909398