For one, I don't have lighting at all in my level. Models are practically unaffected by them. I've played with some of the values but didn't get anywhere. Here's what I have it at this moment:

Code:

---

var detail_size=4;
bmap detailmap = <roughnessstep2.tga>;

function BG_roughness()
{
	bmap_to_mipmap(mtl.Skin1);

	// Adjust the scale of the textures
	mtl.matrix11 = float(18); // default u scale
	mtl.matrix22 = float(18); // default v scale
}

material roughness
{
	/*
	ambient_blue = 255;
	ambient_green = 255;
	ambient_red = 255;
	emissive_blue = 0;
	emissive_green = 0;
	emissive_red = 0;
	diffuse_blue = 0;
	diffuse_green = 0;
	diffuse_red = 0;
	albedo = 50;
	alpha = 100;
	specular_blue = 0;
	specular_green = 0;
	specular_red = 0;
	power = 0;
	*/
	
	skin1=detailmap;
	event = BG_roughness;
	effect =
	"
		matrix matMtl;
		texture entSkin1; // Your big skin tex
		texture mtlSkin1; // A detailmap
		
		technique add_roughness
		{
			pass P0
			{
				lighting=false;//false;
				ditherenable=true;
				zwriteenable=true;
				zenable=true;
				
				alphablendenable=true;
				Texture[0] = <entSkin1>;
				
				magFilter[0]=linear;
				minFilter[0]=linear;
				mipFilter[0]=linear;
				
				TextureTransformflags[0] = disable;
				texcoordindex[0]=0;
				
				ColorArg1[0] = Texture; 
				ColorOp[0] = modulate;//2x;
				ColorArg2[0]=Diffuse;
				
				Texture[1] = <mtlSkin1>;
				
				magFilter[1]=linear;
				minFilter[1]=linear;
				mipFilter[1]=linear;
				
				ColorOp[1]=addsigned;
				ColorArg1[1]=Texture;
				ColorArg2[1]=Current;
				// AlphaOp[1] = Disable; // this might be the cause to the problem
				
				TextureTransformFlags[1] = Count2;
				TextureTransform[1] = <matMtl>;
				texcoordindex[1]=1;
				
				// colorop[2]=disable;
				// alphaop[2]=disable; // as well as this
			}
		}
	";
}

---

Having it like this gives the half transparent effect, but no detail or anything.