We're using mercurial for development, which is distributed VCS. This allows you to contribute patches easily.
If you have done some changes, just commit them to your repo clone (read Mercurial Quick Start to understand basic workflow) and then just send a patch to byteflow-hackers (with a hg email -o -t [email protected]). Please don't forget to describe it (of course, brief description of your work should be in changeset messages, but it would be nice to get more description of why we should apply your patch).
Serving your repository
If you have a place to serve your own repository, you can go this way. ;-) I'll supply more details more, if anyone will need - ask for them in mailing list or in jabber conference.