Andrew,
If this is at a SASS match, then you can't carry or swap out a capped cylinder, just charged with ball & powder.
I have a cylinder pouch that I got from Cabela's. You want a pouch with a flap, to keep out any possible flammable particles. A chainfire in a belt held charged cylinder could get ugly. The club would also let you stage the cylinder, I imagine, but that's dependent on there actually being a place to stage it. If you do stage it, make sure your not going to be shooting right over the top of it, for the same reasons as above.
As far as the reload, I would just pull the spent cylinder, replace with the charged cylinder, and cap the gun. The spent cylinder can go into the pouch or a vest pocket. I would just practice the swap at home (with empty cylinders, of course).
Good Luck!