Today I've implented a new material for the terrain. The multitexturing is now based on a shader, not anymore on fixed functions pipeline effects. The shader needs PS 1.4. The old FFP effect is still there as fallback if your videocard doesn't support PS 1.4. This new multitexturing material based on jcl's shader from Wiki, but with more textures and a real rgb blendmap. The 4 external detailtextures and the shadowmap is the same as before. But the 3 blendmaps are now stored in one rgb blendmap. This saves a lot of diskspace and makes better framerates and (a bit) faster calculations in the editor.
The shader doesn't need alphachannels to blend the textures like the old ffp material. So now you can use stencil shadow on terrain!!.