Shame on Mark for posting it on the "official" forums! It is also in the "official" thread.
In the official forums which not everybody visits (whether good or bad), in the Module Tweaks forum (whether the best place or not) in a post mentioning a README in a SVN directory which happens to contain an FAQ but is for Advanced Users only so people might not read. Arthur Dent's House Destruction plans were more obvious to find.
Just in case :
***** Some FAX *****
Q: What's the idea behind this?
A: To provide users with the latest, bleeding edge tweaks and fixes, and to improve the quality of BlitzMax by allowing the community to test it for us!
Q: Is it going to replace syncmods?
A: Yes. However, syncmods will still be available for BlitzMax versions 1.28 and earlier.
Q: Will there still be binary updates such as BlitzMaxUpdate128_Win32_X86?
A: Yes, and they should be more solid than ever as they'll have received much more testing.
Q: Am I supposed to SVN my current v1.28 installation, or is this to be tested separately (in a different path)?
A: You should install the SVN version completely separately. It's OK to have multiple versions installed on the same machine.
Q: Can I install the SVN version to somewhere apart from c:\blitzmax.
A: Yes, but for the sake of simplicity these instructions will assume you are installing to c:\blitzmax.
Q: Things look okay until I try to compile and get: Can't find interface for module BRL.Blitz
A: You need to rebuild modules.
Q: Where can I find out more about subversion?
A: There is an excellent online book here: http://svnbook.red-bean.com/