Success! I can access Tablet SDK functionality from Java. Rather than use COM, my original tactic, I did what I joked about: used C++/CLI so that the call is Java->Unmanaged C++->C (Win32)->Managed C++! Pretty funny, but not all that hard to follow in the source code. I have to say, I'm going to guess I'm the first person to write code to convert a jstring into a char* and pass that into a gcnew System::String!
Look for an article on DevX by the end of the month.