Someone told me that you can't use these shaders without an Nvidia videocard, and the system requirements are quite high. That means they aren't any good for a commercial game, or anything you want to distribute. It's not even any good for you personally, if you don't have the right graphics card.
I'm not sure though. I don't know anything about it. You don't even need to use this really though. Just use set(my,SHADOW) for and entity if it's not high poly. Plus, there are plenty of shaders that already produce shadows, and also support other techniques. Try the bump mapping shader w/ spec mapping support. I use it for almost everything.