Huh, I didn't realize Wilbur had an altitude shader! Well anyway, to answer your earlier question Kyrel, I should have specified that I created the gradient maps in GIMP, which is sort of a scaled down Photoshop clone. I know that you can create gradient maps in Photoshop but, not having ever used PS, I'm afraid I couldn't tell you how to do it. But basically you import the Wilbur height map, make a copy of it, and then apply a gradient map to that copy.

Cheers,
-Arsheesh