Full manual. You'll need a tripod. The results should be stunning having the people lit by nothing but the fire.

I've only shot one camp fire before and was very pleased with the result, I was also using a SRT 102 a 35mm manual SLR with a 50mm f/1.7 lens. The trick I did was using colour film (Kodak HD ISO 400).

I setup my camera on a tripod and attached a cable release. First shot was at f/1.7 and a four second exposure using the blub setting. I reset the shutter without advancing the film, and did a double exposure, shooting a f/1.7 at 1/60 over top the first one.