Haven't you tried the Advanced Terrain Plugin?
It uses a heightmap, a nice high res detail map, and a colour map.
The colour map is drawn over the terrain and is used for showing areas of grass and sand for example, like an overlay that colours the detail texture to suit.
The detail map is used as the actual texture of the terrain, a bit like making a massive plain and scaling it's texture so it repeats several times.
You should check out the topic in the DBP forum.
Van-B

It's c**p being the only coder in the village.