Have been digging around for a solution to this myself, and you have two options - use iTunes to rip apple lossless with error correction on, or run a windows application (like EAC, media monkey, whatever) under a Windows install in bootcamp, then import those files into iTunes.
The latter seems a bit of a faff to me, when apple lossless is, to all intents and purposes, just as good, and you have to use iTunes to control airport express/airtunes anyway.