Some tricks I've seen and used....
The one I've used...
Get one of the little air mattress inflators (easy to find at Wal-Mart and many other places). They have both battery operated and ones that plug into your car adaptor. Get a length of pipe (recommend at least a few feet long, might want to use something as a heat sink if it's going to stay in the fire long) and jam one end of the inflator adaptor in there (doesn't take a very tight seal to work well). When I had to use this, it worked beautifully as am improvised bellows after gathering the pieces from people at the event.
Another one I've seen (Ron Hood's video, Survival Camping) was using a trash bag with a fiberglass pole curled up inside as an expander to create a basic bellows. I think they left one end open to let air in, then squeezed it closed while compressing the bag to force the air out through a tube into the fire.