Correct me if I'm wrong, but I assume that if a ROM isn't emulated by anything - as is the case with Infernal Machine - then there's no possibility of ripping music to .USF from it, either?
I seem to remember reading in an interview that IM uses streamed audio, as in F-Zero X, Magical Tetris Challenge, Excitebike, et al.
If it doesn't work in Project 64 there's very little chance of getting a working USF. Maybe 1.7 will provide support, though, and that might be integrated into a future version of the tools and 64th Note.