Nevermind... I have my answers after looking through the install.php script code and assorted HowTo's.
Simply put, ISPConfig multiserver setups are envisioned to be run on a local network. There are no security considerations built in to ISPConfig's database replication and sharing functionality. That's not to say it can't be done, but rather there's nothing inherently built-in to ISPConfig itself to do so.
Last edited by SunnyD; 24th April 2013 at 06:38.