I was doing some work earlier with Piotr (which has now stalled for some reason) on implementing MFC. We settled on an approach where I would use the MS headers to describe to him the ABI without implementation details (by writing headers and test cases mostly), and he would implement the actual library.
The ATL headers are related, so I should be able to at least get you the correct struct layouts for all versions.
I may also be able to build test programs in MSVC, if that would help.