The best thing to do is download the developers virtual appliance from the website and use that to learn the system. Or you can download one of the packages from the wiki page:
Short answer: Maintain your code in git, publish branches somewhere, let us know where in the trackers / fora. If using Git is an issue, we can also accept patches (roughly: the output of the unix “diff” command) but can be a bit more work on the integrators, and everything will go into Git eventually.
juggernautsei
Where can we get a copy of the v4.0 to work with?
A git repository is going to be your best bet. We don’t have an automated process to build “nightlies” or something like that. We do have a demo if you want to see what you’ll be working with.