A professor of fish medicine at N.C. State College of Veterinary Medicine has done this in several cases with very good results. He thinks that the peas somehow encourage destruction of the impaction. No hard scientific data yet, but it's worth a try. Fast your fish for a couple of days. Withhold all food for three or four days, and sometimes this alone will break up the impaction and return things to normal.
Most fish can go a week to ten days without food and be just fine.
Periodic aspiration of the swim bladder works very well. Basically, you stick a needle in the swim bladder and suck out some of the air. Not something to be entered into lightly, but does work well. This is not a cure, but a successful treatment. The head veterinarian at the Baltimore Aquarium prefers this method.