Also, set your camera viewport so it's square. So, for a 1024x768 screen, your going to want to use a 512x512 texture, so set your camera viewport to:
CameraViewPort camera,0,0,512,512.
Then you simply copyrect 0,0,512,512 :o)
CameraViewPort camera,0,0,512,512.
Then you simply copyrect 0,0,512,512 :o)