from what i've heard back in artist feedback, it is difficult/impossible for the average indie artist to get in there. most everything needs to be a record label that deals directly with the iTunes store. the application to be an iTunes record label requires a 20 album catalog to start. . . i don't know the exact criteria to get the access, but i would also assume the source material would have to have non-padded zero resolution above 16 bits (24bit more than likely and not just up sampled from a 16 bit source) and any sample rate 44.1kHz-192kHz. on top of that, the files would have to pass the afclip command line utility with no samples clipped and no inter-sample peaks to qualify. again, i don't know for sure, but i would assume the tools they make available through the MFiT program are actually used as benchmarks.
i'll keep looking and update if i find a definitive answer
- nick