Most fixed frame screens these days use a Z-bar or French Cleat.
I would suggest you pick one or two up at your local home improvement retailer and see if you can make it work.
On one of my last screens, I didn't even need to attach the mated side of the z-bar to the frame. I just attached one to the wall, and there was a groove in the frame itself that worked perfectly. Otherwise attach the other side to the frame and you're all set.