In Visual Studio 2010, I'm trying to build an COM-interop enabled C# project without registering it during build, but I DO require the assembly's typelibrary (.tlb) file, so I can import it from another C++ project in the solution.
I haven't found a way of doing this - there once upon a time was a tlbexp.exe tool, but it was deprecated in favor of regasm.exe /tlb (which unlike tlbexp.exe, registers it).
tlbexp is still available in VS2010 here: