Screwing down a radio

So I am trying to fit radio in and would like to screw the frame down so it's more stable. But I am at a loss how to do it... I can't get a drill in the area to drill a hole for the screw, and even if I could there is no room for a screw head when the radio slides in...

I have heard this is possible but would like some advice how, thanks!

If you're going to keep this car for a while or sell the radio with the car you could try glueing it in there. I know it's ghetto, but if it looks ok and does the job it's better tha spending $100 for a new dash piece.

Yeah I don't like the thought of something as permanent as that and I will probably be keeping this stereo when i sell the car, thanks for the idea though.