Soak hickory chips in a bowl filled with water for several hours or overnight and then place them in the metal can.
Cover the top of the metal can with enough aluminum foil to extend down the outside a couple of inches and twist-tie it into place with metal wire.
Punch holes in the aluminum foil to allow the hickory scent to escape.
Put the can in the fireplace. Find a secure spot for the can to sit on the floor of the fireplace where it receives plenty of heat from the gas logs without touching them.