Those of you intrepid enough will find a ProjectBuilder version of MaxUAE 0.8.22 Beta 1 in the CVS repository. Checkout module "maxuae-0.8.22" to get it.
This version is complete with the uae-0.8.22 code necessary to build it. AFAIK, you should be able to compile it straightaway. As this is the first time I've put up a .pbproj, please let me know if there are any problems.