I'm not sure I understand what the problem is. Are you saying the AMS machine is not going to have an Internet connection anymore?
That shouldn't be such a problem, actually. We can configure the AMS to sync the contents of its mirror with another machine on the LAN (instead of our Internet servers).
Would that help?
Alternatively, you could deploy a 2nd level mirror on a machine that has an Internet connection, tell it to sync its contents directly from the Internet (as opposed to syncing it with the AMS-based mirror) and finally tell all the machines on the network to use that mirror instead of the AMS-based one.
Thanks
Vlk