Aaaah, one of those type of folk are we? Yes yes, we had those type of people on the S2000 forum.
Believe you me, i googled before I asked... loads of threads on the old Z4, couldn't find a sausage on the E89.
It look like the bumper is mostly clip in with a few fixings that i can see, would be a good effort if you could do a 'how to' to help the next person, good luck