I have had great success cinching up these chains without the tool.
Put the master link in from the back so that the pins are toward the front. Rub your finger over the link plate, you will notice that one side has sharp edges and the other rounded edges. Put the plate in place with the rounded edges forward. Place a body dolly or large hammer behind the link to back it up. If you're not slightly ambidextrous, you might need a helper to hold it firmly in place. Then use the ball side of a ball peen hammer and begin peening the ends of the master link pins. Keep hitting them around the outer diameter until they peen out to roughly the shape of a carriage bolt head.