plone – How to make folders accessible for only certain users
this was a requirement we had at netsight a while back and we worked it out, but never got round to documenting how we did it. In case I forget, here is someone else describing exactly the same solution
(Summary: in ZMI create a new role, then remove aquired priveleges for protected folder and assign approprite priveleges for new role, then in plone go to sharing tab for folder and add selected users to the role)