Hello,
It would be better to create a .dll with you MFC application and use LabVIEW's call library function. The CIN is only compatible with MS Visual C++, Semantec C, or CVI, and I am not sure if these are MFC compliant apps or not. The call library function in LabVIEW you can export your functions in the .dll and will not have to worry about multi-threading and other issues about compiling with a CIN.
Here is a link to additional information:
http://digital.ni.com/manuals.nsf/caba5d53e9b015a186256793004eebb7/4f1447f7cd83d6d88625690d00637ced
Doug
