There is no way to share the drive by attaching it to two computers. This may, in fact, ruin the computers and the drive. A better idea would be to use file sharing to share the information on the drive. If you do not already have a network connection, you can run an Ethernet crossover cable between the machines. You can share FireWire hard drives using the bus, unlike USB.
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Simon Kornblith
Computer Consultant
Programmer