I didn't consider this use case when creating Insight. Whilst it sounds feasible, there are a bunch of places in the code that assume either JS or CSS based things. This isn't always for great reasons, it was just simpler at the time.
Unless there are other people also wanting silverlight support in Cassette, I'd say for now, roll your own solution. Grab any useful bits of code from Cassette where it makes sense.
I'm collecting a list of things which are hard or impossible in Cassette right now, in preparation for v3. Additional bundle types are now on that list :)