Under Linux you are given no access to the RSX. Also you only get half the ram. To emulate a system properly you need a system roughly 10 times more powerful to do so efficiently.
There is no N64 emulator made with the ppc architecture. Even if there was it would run like crap. Snes9x, FCEU, Dgen, and a few others are the only systems you could emulate. In other words 8 and 16 bit consoles.