Here are some tips for people joining the Nucleus Core team on SourceForge with no knowledge about CVS. It is not difficult to commit improvements to the core.
Here's a small “howto make a commit”. Feel free to improve it.
cvs -z3 -d:ext:*****@cvs.sourceforge.net:/cvsroot/nucleuscms co -P nucleus
→ Change * by your SourceForge login. You'll be asked your password. Type it and the repository will be downloaded.
cvs -z3 -d:ext:rodrigomoraes@cvs.sourceforge.net:/cvsroot/nucleuscms commit nucleus/install.sql
→ In this example I've committed install.sql, and the path (nucleus/) is relative to the directory I was browsing in the command line in that moment.
→ detailed instructions on how to use TortoiseCVS on SourceForge are here: http://sourceforge.net/docs/F04/en/