This thread describes the method.
Thanks Chris. Sorry I didn't respond earlier, I've been offline for a couple days. That link that Chris posted roughly describes the process. Basically, I setup the camera on a tripod and take between 5 and 8 shots of someone's drive (my camera will take a little over 4 frames per second. After I get the film developed I scan it, and then take it into Macromedia Fireworks (similar to PS). In Fireworks I cut out the bodies carefully and layer them accordingly. Because all the shots are done with a tripod they have identical backgrounds so lining things up is easy.
That's pretty much it. I've done this about 10 times and I'm getting a bit better at it every time I do it. Takes 1-2 hours to "photoshop" everything together.
Thanks for the comments.