I finally have the anti-cheat shader working! These are the results (you may need to increase your monitor's brightness to see the difference, as this is what the shader is designed to combat):
The fixed version is to the left, and the original is to the right.
Ironically, I kind of cheated to get these examples (it is a simple quad with a screenshot slapped ontop of it), so I can't see how it looks interactively. But I plan on using this for future projects which require this kind of protection, so I should have an excuse to try it out eventually (probably during one of these quick test projects I will be creating).
P.S. Adding images to a post on Blogspot is somewhat annoying. I had to restructure this post several times before it was formatted correctly.