I -used- to be able to scan in Classic using Vistascan (although there website says this is impossible, which is impossible, since I was doing it). Because Classic USB devices are still fully functional in the classic layer (as opposed to firewire devices, which are not) you should be able to just load it up and go.
I can't really get too pissed at umax for not supporting their scanner- I payed dirt cheap prices for it. If I ever get a new one, though, it'll be an epson. I've been -really- impressed with their performance and color reproduction. And their software doesn't cause aesthetic-induced spasms.
I'd love if Apple introduced a new scanner interface (ALA Twain, but not sucking) that would offer the most standard functions for scanners so we wouldn't have to deal with scanner makers anymore for software... in particular GUI interfaces... UGH.