it should work... have you changed all the texskins to entskin? did you set the tiling parameters in the terrain action?

action terrain
{
my.skill41=float(10);
my.skill42=float(20);
my.skill43=float(5);
my.skill44=float(10);

my.flare=off;
my.transparent=off;
my.material=mat_terrain_multitexture;
}

btw. it's very easy to add an additional detailmap or such things to this shader...