Great stuff!
I have to caution you about what you're trying though (covering to dotcover format for TeamCity import), because when I tried to do this myself, I couldn't get it to work :(
Firstly, the data is in a different format (NCrunch is by source file where dotCover is by method/class). If you manage to overcome this though, there still seems to be some level of integration between TeamCity and dotCover that goes beyond a simple file format. I'll be excited if you get this to work, but I recommend doing some careful testing before investing too much if your time.