I've heard of guys using an old propane tank with some extra 'fittings' to attach a regulator and air hose. Not sure what the safety issues would be, but some sort of 'air tank' like this is probably the best and easiest. For filling the tank, you can either take it to a gas station, or buy one of them little 'spare tire' compressors that are usually at auto-type stores. I've seen them at garage sales and discount bins all over the place. They usually plug into a cigarette lighter socket and will get the tank up to pretty good pressure. It works pretty slowly, but it's easier than carting the thing to a gas station. (this would work if you were using the 'inner tube' or 'spare tire' tank as well.
M.