I've been able to create a signed CAB file for web deployment containing my control and dll, but my control seems unable to access classes and functions in my dll even though it is listed as a dependency in the CAB's inf file. For all my research, I can't even tell if what I'm trying to do is "allowed". Followup: if it is possible to talk to a non-com dll, is it a security risk?
I'm using msvc 2010. Thanks for your time!
Pretty certain what I was trying to do wasn't possible. Ended up creating a class library instead so that I could reference and include the functions I needed at compile time.