I can't find any info on this so forgive this potentially noob question.
Is it possible to paint the Flat normal colour on a new layer and see the results in realtime? I don't want this to be a destructive thing, so new layer is essential. As far as I can determine the only way to paint flat normal information (RGB 128,128,255) is to do it with the Normal Map in the diffuse blending modes, which isn't ideal as you can't see your results of the normal map in realtime.