I got the compositor working. It's fully scriptable so you can turn on and turn off compositors when you want to. Here is a simple edge detection compositor that sharpens the edges of the models to give a more defined look. I also included a couple of other samples including night vision.
For those who compile the code...you can use any one of the compositors in the media\materials\scripts\Examples.compositor script. The list is:
Bloom
Glass
Old TV
B&W
Embossed
Sharpen Edges
Invert
Posterize
Laplace
Tiling
Old Movie
HDR
Gaussian Blur
Radial Blur
ASCII
Halftone
Night Vision
Dither
I updated the binaries to reflect the addition of the compositor. Please download them again.
Those effects are assigned to keys via the main.nut script function "onKeyDown()".
There are more. The list is in the original post in this thread. You can edit the main.nut script to assign a key to the other effects if you want. You can also make your own if you are good with Ogre and shaders. Check out the documentation for the Ogre Compositor framework.