Sorry mate, i don't have my car at the moment. Just use a tiny drill bit, and make a hole that's only a couple of mms. You can remove the lights and drill on the bottom if you're worried about it being visible, or you can just do it where it's (barely) visible. There's no real method to it, just any tiny holes to allow built up moisture/condensation to escape will do the trick. Sorry I can't get a picture, but you can't really go wrong.

