OK, I took a few pictures of the hardware I used while the screen was still up on the wall.
Here is a shot of it from the side, brackets mostly closed:
And here is the same piece at about maximum extension (although not secured):
Finally here is an image from the top looking down:
These are inexpensive brackets made for mounting blinds.
As you can see, the brackets have channels molded into them and long narrow openings running down their length which make them ideal for this type of application.
The mount is made up of two of the exact same bracket. One is bolted to the wall and the other to the screen. Once all eight pieces have been secured to the correct positions on both the screen and the wall, the screen should simply slide forward onto the wall brackets.
Once it is up, you adjust the screen to the desired position and run a simple bolt and wing nut through the holes to lock it in place.