I was able to see it in action yesterday. Clover can be run either as a standalone program or a workspace plugin; either way, you either load up or select a project, then explicitly compile and execute all the test cases. (This step shouldn't be hard assuming tests can be run in batches in C# as well as in Java). Clover will then generate an image/pdf/Text file showing all the code that wasn't referenced by the test classes.
It looks like the commercial version is mightily expensive, but there is a free trial version that should do the job. Looking into Open Source alternatives as we speak.