Surefire Clover Coverage Report as of December 10 2007 (attached) attached
For the record, I started by specifying a special local repository in my settings.xml.
Then I tried just using maven-clover-plugin 3.6, calling instrumentInternal directly (which you're not supposed to do because you risk getting cloverized stuff in your production output, though that's exactly what I wanted to do in my case).
That didn't quite work because instrumentInternal includes a function redirectArtifact() that changes the output jar to be blah-clover.jar; once I commented that out and added clover as a dependency to all of my code, I was able to run my integration tests and get a total view of my integration test coverage.
For the record, Surefire's unit tests covered 45% of Surefire; with the added integration tests we've covered 79.4% (87 classes, 3,323 / 4,187 elements). It also highlighted some key areas where we could add more tests, which was exactly what I wanted.