Here's the underside of the top grill. There are four screws and some plastic tabs to hold the metal part in place.
http://i61.tinypic.com/295poc9.jpg
Anyway, here are the final pics (until I water cool my GPU) of my case, now that I got my fan controller (old one wouldn't fit):
http://i62.tinypic.com/ipcmxc.jpg
http://i60.tinypic.com/4vijjp.jpg