Ok, since Apple won't release the hardware tech sheets or what ever, thus making it near impossible to write an OS for the hardware...
...why not do something like Magic for Atari? They made an emulator or something that allowed you to run Atari compatable Magic apps on a Mac, from within MacOS. The funny thing is it ran a hell of a lot faster than the OS it was running within, only problem was that everything was German. :/
EDIT: Found the link:
http://www.application-systems.de/magic/