for those who prefer "manual" way of doing things, here's an idea.
1. duplicate the 'adminstrator' group. don't format your title. just make it look like the registered user group. but give administrative permission.
2. register/make a new nick and put this under the newly created admin group.
so it will look as if there is no admin online because u will appear like any other user.
there you go. secret, undercover admin.