You can make a test install of 6.5.1 and play around with things there. <img src="https://www.ubbcentral.com/boards/images/graemlins/smile.gif" alt="" /> (This is permitted under the license.)
You'll also want to read
this topic on UBBDev, which has some additional information on the process... it's actually quite out of date now, but it should give you a more general idea about what's going on.
