so i guess the only way its going to work is to run ppc/wosUAE on workbench and run the game you want. as that'll give you the level of abstraction required to use USB controllers. can't say how fast it'll be... :-(
at least you'll be able to use the mouse in the early startup menu, and booting off of floppy into something like Dpaint, you'll still have USB available...?
wait a sec, what about bootng off of USB CD?