isnt their no way you could put each plant in a bag and seal the top then pump the co2 in via a hose, you could get the cannisters of co2 and pump this into the bag and it should be sealed enough to kill them, i dont think you could implement this for a whole room, but if you only had a low number of plants then im sure you could find some big bags and sit the plants in and tie the top and suck what air is in their out, then fill with co2, i dont think it would take long to kill them all either this way, but you would need a bottle of co2 and some air tight bags possibly that let light through to prevent any dark period, i know you can get big clear bags on a role that would hold a bigish plant, but it would mean buying co2 im sure you could pump it in via hose and leave it to sit and top up as needed to keep the bag inflated, this should prevent air getting in as long as the bag stayed sort of inflated by the co2, it could be worth a try if anyone is using co2 to supliment the grow room with, just have to get some bags and make sure their was no rips to let air in else it would be pointless,
just thought id mention it thats all, just in case it is useful to anyone who all ready has co2 in their grow room, i dont think it would be to hard to set up, not something you could do on your own as you would need someone to lift the plant and someone to hold the bag, but if anyone does try it then make sure the air is well vented when you open the bags for obvious reasons