Hello,
It has has been a while since I worked in Zbrush.
I recall there was a way to use polypaint and Zadd at the same time without the alpha masking polypainting.
Any input would be appreciated! 
Thanks,
F
i would also like to know how you use a texture and a alpha of that texture together with zadd and polypaint without the grey of the alpha obscuring the polypainted texture cheers