With MiniVend's GlobalSub capability, very complex add-on schemes can be implemented with Perl subroutines. And with the new writable database, pages that modify the catalog data can be made. If you mark a page as an AdminPage, only the catalog administrator may use it. See MasterHost, RemoteUser, and Password.
In addition, you can create a file in any MiniVend page subdirectory called .access. If that file is present and non-zero in size, any pages in that directory are only available to the catalog administrator.