Hi James,
I don't think a second node is necessary - only a second link from the image node's output to the RGB/BW. Unless you are using another image out of shadermap. What I found interesting is to add after the RGB/BW a math node to multiply the values e.g. by 5.
Re: unwrapping - one of my weak points...
Another thing I noticed is the lighting - whatever I change seems to have no influence at all. Besides only 2 lamp types are currently supported with cycles - point and sun.
It could be that emitting planes are prefered to lamps ?
Anyway here's my first experiment - the good old sphere with one of your repper-tiles.
Attachment 86082