I\'ve set myself a new task which involves \"spying\" on COM objects.
Even if you don\'t do COM, you\'re probably familiar with API hooking techniques where you can
I don't have a definitive answer, but I know a guy who might :)
Jonas Blunck's tools are all about interception at different levels, his ComTrace is based on Keith Brown's technique, if I recall correctly, and sounds similar to what you're doing, except he parses type libraries and headers to keep track of interfaces dynamically.
We wrote Developer Playground together (I mostly did UI), it's based on API hooking, and I know Jonas said he wanted to rework ComTrace to use the same API hooking library, because it gave the best "resolution" for interception.
I don't know what you want to use this for, but I suggest you check out Jonas' tools and shoot him an e-mail - he might be able to prod you in the right direction.