You could buy some car batteries and possibly take an old power backup unit and use that interface with the car batteries, then hook this bad boy up with a FW800 out to your laptop and you'd be set. Just power the thing up and down with use...
Might wanna consider some wheels for carrying it around :P
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"Fix it 'til it Breaks."
Jacob - EiC & Director of Technology Mac Pro Quad 2.66 - 4GB RAM 160 GB SATA RAID 1 - 650 GB Storage Quad 19" Widescreen LCDs Accessorized to the Hilt