Something I've been working on...
http://kolis.dyndns.org/ed/prog/sweetpotato/index.html
It's going to be sort of like DoGA, only no animation, but you will be able to assign multiple colors to a single part... and I think there's a Java-based boolean operations library out there, as well as a .X exporter, so it might even be useful for SE5, if I ever finish it
