1. have a look at the CoverStory Howto,
2. download CoverStory,
3. open (with XCode) the XCode Project you want to measure,
4. run the script EnableGCov.scpt linked to from the howto,
5. run your tests and see a linker error, – dead end for the time being. http://groups.google.com/group/coverstory-discuss/browse_thread/thread/fbcbf5ed61d8d02b#