What i did was just created a category that is only viewable by registered users. If you already do that you might have to create a new user group (other than all, admin, registered, and registered(validating), and edit the members you wish to be allowed to view the new category set to the new group.
Go to admin panel - create the category - set the view category, view image, download to registered users, upload/download to admin (since i don't have it set up for others to upload to) n.n;; and the rest all registered users.