indiGLOW: Adjusting your normalmap will need to be done. There is no real "depth" adjustment. There is not even specular or self-shadowing in this effect so it is pretty basic.

Grimber: To me it seems a combination of normalmap values, and possible the overall light directions.
1). try changing c12.y in the vertexShaderConstants to a lower number like 0.2 and see what happens. vertexShaderConstant[n] = {x, y, z, w,};
2). Change the sun position and elevation and see what effect that has.
3). Play with the normalmap.

Both textures do not need to be the same format (ie; bmp or tga only).

My cube on the left has no normalmap, just entSkin1 applied.
My cube on the right has the normalmap in entSkin2 applied to entSkin1.



Eric