Install Mountain Lion to another drive without rebooting I'm wondering if its possible to install Mountain Lion to an external drive (connected via esata) without rebooting from the host system?

I came across this hint suggesting that it was possible to do with Snow Leopard, but this method doesnt work with ML.
Not really, but once you install a clean Mountain Lion system, you can image it to a DMG file and the clone it to your heart's content without rebooting the system doing the copying.