Ok i tried what you have said, i imported the basemesh in z-brush then stored this as a morph target.
Then i went a couple of subdivisions higher and added some detail then i went to tool=> displacement and made a displacementmap, but nothing happens and if something did happen i can't find the displacementmap.
I try to make a displacementfile in mudbox yesterday also but this gave a very strange picture.
The picture below shows how far i am with the details and for a z-brush firsttime i kinda like it.