I started this project as a study of Projection Master in ZBrush. For the alpha in ZBrush, I created a high contrast image from a picture of a Mayan calendar carved out of wood. I then used Projection Master to place the image on the mesh. From there, I sculpted in detail, painted with Poly Paint and used UV Master for the UV layout.
The mesh was then exported using GoZ into Max. I created a low poly mesh in Max and projected the UVs from the high poly on to the new low poly mesh (a bit of adjustment was needed).
The image below is a screen-cap from UDK. I placed it into the demo foliage map.
ZBrush Poly Paint