Do you know how close the USB implementation is to Linux's?

Totally different. It does not even resemble BSD's as I understand it. Apple built their own driver system for OS X. Nothing happens when you plug the empeg in to an OS X box with USB, no log messages, no new dev entries, nothing. I think you would need a kernel module to support it. Now kernel modules for OS X are supposed to be easier to write than for you average *nix, but I bet it would still be a lot of work :-(

-Mike