Terrain Splatting

Anyone know how to use more than 4 detail textures when splatting terrain? It seems the limitation is that you can only have 4 channels for the blend map. Has anyone seen another approach?

Just add more. Each blend map has 4 textures, so try to keep the number of textures to a multiple of 4, since each map slows it down. i.e, having 5 textures for example, and not using 3, would be a waste.