Old PC? All my old PCs have X86 processors and they're running Linux. Are you saying there are sources of extremely cheap PPC motherboards to stick in a PC chasis?
Sorry, a thinko :) I meant an old PPC machine....
Bochs has full support for Mac OS X including a .dmg binary on their download page, so the port for that package is done already by the Bochs team. The tricky bit will be going from Bochs virtual machine approach to an in-process extension sort of deal.
Yeah. From what I remember, Bochs uses only software emulation, which means it's very slow but very portable. Ideally there would be a libbochs that lets you pass in a block of code of any given architecture and have it translated into any other architecture. If there was such a library (not sure if there is) it could be integrated with the Wine PE loader code. Possibly.