There's no reason why you can't add an extra "shaded" pass to this shader. You can do shaded passes in customlighting. You could just multiply your diffuse with the shader near the end. You could also integrate the same shader instructions into a diffuse pass. It won't have quite the same effect but will still work.
nevermind about teh last post, somehow I got it now =) But I have a question, I made a toon shader that is connected to the diffuse and the lighting model is prefered to be non_Directional, but to pull this halftone it needs to be custom lighting... any recomendation to blend the two? I've been thinkign about masking so…