Hey,
I remember in Zbrush 3 there used to be a Warp Mode in the Brush Palette allowing you to create tileable textures. Anyone know where that went or if it was renamed ? Sorry, had about a year of working on a Mudbox show, I am not up-to-date 
EDIT: Found it Brush: Curve. Hey and there ARE Blendmodes for Polypainting, I did not know that. Brush:Alpha and textures/ PolypaintMode. Nice.