if youre planning on using zbrush for jka, id like to point oit that any versions past i think 4.0 seem to warp the uv's, this is known by pixologic and they are working on it
I finally just made a cube with uvs, imported it, and use it as my yest subject and everything i try or research end up with the exact same results give or take some nudges by smoothing. If i subdivide it in softimage a few times it lines back up