This demo uses a modified version of the vertex color splat script, instead of the detail layer there is a shading layer.
http://uploader.polorix.net//files/7/B6.blend
The Z transperancy feature worked better for me in blender 2.43 preview 11c, found here
http://www.continuousphysics.com/Bullet/phpBB2/viewtopic.php?t=752