OK. Not a ZBrush Tut’ but written from a ZBrusher’s point of view. 
It’s a step-by-step, on how to use Blender to UV unwrap OBJ’s.
Presently parked here…
http://homepage.ntlworld.com/ross.inglis/UVTut/index.html
I’ve not done anything like this before. So there ARE probably goofs.
If you try it and find problems, feel free to post rep’ here or pm me and
I’ll fix 'em.
G.