Amazing, Monkeybrother ! I'm definitely interested in testing your modified file, please :)
Regards.
Sure, attaching .osl file. It seems to be a bit sensitive, as in you have to do things the right way. If I made a big subdivided box and added a "per face" uvw map, it doesn't work (even if I unwelded vertices or even detached every face), and if I resize the polygon after applying the uv map it stretches and bends (it shouldn't happen, but I haven't investigated). So for best result: create a plane with the correct size, apply material and uv's ("per face" or "planar"), instance it. I've just done some quick tests, so I'm sure there's an explanation.
I'm not 100% sure that the attached file is the latest one, the one I'm using, but let me know if it doesn't work. Hopefully someone can make a less hacky version.