We use the exact approach described by specbill above with the exeption that we're left foot down. One thing I might add is that I always make sure to approach the stop with my right foot at the bottom of the pedal circle so to minimize movement of my body as I stand down.
As noted above, it takes practice.....one other thing....if you're wearing road shoes, I highly recommend that you ditch them for the tandem in favor of mountain shoes. The last thing I want to do is slide when I'm trying to stop the bike with Pam on behind and I feel about six times more confident in shoes with some grip to them. Others may differ....