OK, I've had another look and I have to admit I was wrong with the previous post. Sorry. The instructions that came with the shader are pretty confusing:

The section that deals with editing the the maya.rayrc file is badly written. It doesn't say what should be added, just 'make it look like this'.

And the maya.rayrc file is confusing too. I'm think that the lines with '#' are remarks. So what are the registry entries doing with '#' stuck in front of them?

Is the maya.rayrc file supposed to start only when there are custom modifications and addons?