My IM has four small screw-in type bolts. I took mine off last year to install my homemade 'pop the hood' kit.
If I remember correctly, I used a small socket. Taking if off was easy but it was a PITA to put back on. I'd get three sides flush and the remaining side would not lie flush with the body. It didn't matter which corner I did last. I fiddled with the damn thing for what seemed like hours. When I got it about 90% right I quit while I was ahead.
I asked myself and number of times, "How can something that looks so easy to install be so hard?"
Whit, can't you get a small allen wrench/key in there?