Thanks, but I'm afraid that's not going to work in this situation.
To break it down, each RainbowWool blocks needs to have it's own metadata storing the dyes that it was crafted with. There are too many combinations (16 types of dye, 8 empty slots in crafting table) to manually do textures for each combination, not to the mention the about of space that would take up. Since the block will not be using a texture, I need to override the MC rendering stuff using ISBRH and do each one manually based on the blocks metadata. I've also got a feeling this is going to be very resource intensive, but I'm not sure.
If there were only perhaps 4-5 different combinations, that tutorial would be really helpful, but alas, no :(.
I'm starting to realize how difficult this is going to be, and am considering dropping it for a while.