See this thread http://forums.pinnaclesys.com/forums/thread/304771.aspx
There is discussion there about how to run it off a battery (the person who originally posted does that). Basically the power required is 5vdc at at least 1amp (the wall plug is rated at 1.5a). There are several ways you could do this.. from a home-made battery/powersupply to an item you might purchase to power external usb drives available on amazon and other places. The limitation would be how long you can run for. For example many of the available battery supplies are rated at 10-20W, and might run your PVT for a few hours or so. One example might be something like "Power To Go Cordless AC/USB Power Supply".. but I do not own such a thing and only mention it as a example of an item that might work..Ideally a device to power the PVT would have an appropriate connector for power-in and have 5vdc power out.
In theory you could rig a big-ish battery and power both the PVT and your camera with the correct regulators of course.
Let us know what you decode to use.. I'd be interested in knowing