A simpler solution would be to only place the MNC and MNR files on the server. If AutoCAD does not find a MNC and MNR file for the corresponding MNS or MNU, it will create them, by default on the local system, in the local path for menus.
Store the MNS file in a safe place and only use te MNC on the server, this way no one can modify the menu without the admin's approval.