smoosh method

So I have heard great things about the smoosh method when introducing chins. I have decided I would like to try this method. I have a 2 1/2 y/o and a 12 week old to introduce. However I don't have a show cage, so is there something else I can use?? And I know to supervise them and only leave them there for 15 minutes. But if they bite each other do I take em both out immediately?? Also what other things do I stop and end t method for the day??