This is, BTW, the only cutout I made to the video case. I didn't make a cutout for the PC card since I don't travel with one installed. Photo close-up of the power supply plug. Although I didn't, it would be a good idea to mount some sort of rubber material on the inside of the power plug to prevent scratching. The battery pack - not very pretty, but it works.
Size is an issue, the whole thing has to fit in the pocket at the spine of the case.
Currently, the battery pack just sits in there, I don't have it secured with anything. I started out with a 2-AA holder with a 9V snap on top, purchased from Radio Shack. When I stacked 3 together the whole assembly was too long. Next, small scraps of perf board were epoxied onto the ends of the battery packs to act as spacers for the wires. Additional epoxy was dripped in between the packs to seal the soldered wire jumpers.