You can achieve trem pull-up ability with three springs (or even more) by shimming the neck and raising the bridge above the surface of the body. This works on any two-post knife-
edge trem... dunno about a 6-screw "vintage" style bridge. You have to raise the pickups a bit as well, but it works.
For some reason, everyone thinks back-routing is the only way to go. Brad Gillis actually started the whole "chisel out a chunk of wood from behind the trem" trend on his old mongrel strat with the original Floyd with no fine tuners. Some players like having the strings, trem and pickups practically flush with the face of the guitar. Personally, i don't care much for it, and i find shimming the neck a bit is a cleaner solution that leaves more wood in the body.
By the way, "home made Floyd Rose" is a bit of a misleading topic... how about "alternate method for a floating trem"?
