Here is the way to use another computers drive.
Transferring files between two computers using FireWire
You can use FireWire to connect your computer to another Mac and have one of the computers appear as an external hard disk on the other computer. This is sometimes called Target Disk Mode.
To transfer files using FireWire:
Shut down the first computer and leave the second computer on.
Connect the two computers using a 6-pin to 6-pin FireWire cable. (If both computers have higher-speed FireWire 800 ports in addition to the standard FireWire 400 ports, you can use a 9-pin to 9-pin cable with the FireWire 800 ports to transfer data at higher speeds.)
Open System Preferences, click the Startup Disk, and click Target Disk Mode. (Or, start up the first computer while holding down the T key.)
A disk icon for the first computer appears on the desktop on the second computer. Drag files to and from the disk to transfer them.
When you finish, eject the first computer's disk by dragging its icon to the Trash. (While you drag, the Trash icon changes to an Eject icon.)
Push the power button on the first computer to shut it down and disconnect the FireWire cable.
If the computer to which you connect your computer is running Mac OS 9, it must have FireWire version 2.3.3 or later installed. Use Apple System Profiler (located in /Applications/Utilities) to check the version of FireWire installed. If it has an older version, get an update at the Apple FireWire website at
www.apple.com/firewire.
I got this info in the help file of the finder under "firewire."
Hope this helps