When I need to use my gas chamber. I use a rubbermaid shoebox. With a hole cut in it.

I then have a paintball 20oz co2 tank with a regulator and a hose that I run into the shoeboxes hole. It works good. I doubt a little tiny co2 cartridge will do the job. Maybe a few of em.
The smaller the rodent the longer it takes to gas em though. Just food for thought. The bigger they are the faster the co2 takes effect.

My 2 pennies. Good luck to you!!