I have a bootable drive running OSX 10.5.7 connected to a powerbook and I need to know how to boot from external drive. I can't choose it from startup disc because my powerbook keeps booting from a OSX installation CD that I have already run. It seems to want to install OSX again. I need to reboot using my external drive to eject the disc from the powerbook.
Nevermind. Got it. option key on startup.
If you simply need to eject a disc on startup, hold down the mouse button (or trackpad button) while powering up the machine.
Change the startup disk under the Utilities menu when booted to the OS X installer disc.