If the air bag system has a tank then it should work for the horns, at least for a couple of seconds. The issue you will have is how much of a blast you can get out of your system before the pressurized air is depleated. At first I was using a small tank for JCWhitney that held about 1/2 gallon and would give me about a 5 second blast before running out of steam.
I'm not too familiar with the different kinds of air bag systems out there, mine just have tire type fittings and get aired up that way, they didn't even come with a compressor. If your system doesn't have a tank then at the least you would have to add one, you won't be able to run the horns directly from the compressor.
Good Luck,
Mike