All you can do with the terrain is alter the texture. There's no way to reduce it's poly count to get that sort of look, although with time you may fake it fairly well.
It used to be as simple as copying one of the terrain types folder and changing the textures around, but I'm not sure if it is still the same since the update.
SPECS: Q6600 CPU. Nvidia 660GTX. 8 Gig Memory. Win 7.
