i mean.. a co2 tank from a paintball gun is the same thing as a regular co2 tank.... except they're small and you'd have to get it refilled much more...
you just have to release the right amount of co2 into the air around the plants. they'll take it in.
its just a can with co2 in it, no different than a regular one. besides the fact that a regular one will have fittings to regulate/monitor it. which you would need to get anyways..