Is there a way to layer aiToon shaders in Maya? I recognise that the aiToon only outputs colour, so using something like aiLayerRGBA or aiMix doesn't work as it breaks the output. I want to layer parts of the eyes as well as dirt maps on a character - which are basically just an aiToon, a ramp on the tonemap, and a transparency map using surface shader to cutout the map.
Here is an example of the work-in-progress look
