Hi,
In lieu of anyone coming up with a free util, the company I work for wrote a piece of software for a client that performs what you are after. It uses group membership, whereby admins are allowed full access, and members of other groups can be either allowed no access, allowed access to cd's only if they contain a specific flag file or, in the case of cd's not having a flag file, be forced to okay a warning that the media is unauthorised and that they are directly responsible for any damage caused by it. Obviously there would be a cost for using it (if it were mine I'd give it to you). Let me know if you want more info - darthurs@hotmail.com