I don't know if this picture does it any justice, but here's something like what I was talking about, you have the stock valve, and then you have the second valve mounted on the back, taking the place of where the Donley used to be, you would probably have to tap both valves, and run 2 bottom lines, to two tanks, and then you would probably have to do something like this, (courtesy of "Bob" on BEOG) to keep the sear from catching the hammer. (the second picture)
	This is my second, sort of revised version of my full auto type thingy, basically you take the internals and switch them around, To make the paintball shoot out the barrel you take makro line, and put it from one valve to the other bolt guide. I dunno if you could actually do that, but hey it's worth a try.