Is there anyway to start-up a computer from a disc image without having to first burn it to a disc. I have a PowerBook and an old Ruby iMac. I would like to be able to make a disc image of OS X for the iMac stored on the PowerBook/external HD and be able to start-up from that so that the iMac's HD can be used for media and not hogged up by the OS. I have an OS X image ready to go, and when mounted on the PowerBook, I can get it to mount via ethernet on the iMac, but it doesn't come up in start-up drive options.