You can track code coverage in Microsoft Test Manager when the testers manually execute test cases. I wrote a article on this last year. It isn't exactly what you are asking for but I think it gets close. I haven't tried it in TFService so I'm not 100% sure it will work there. http://blogs.msdn.com/b/visualstudioalm/archive/2012/11/28/code-coverage-in-microsoft-test-manager-in-visual-studio-update-1.aspx
Mike