Tell him to start at the back of the pack in the swim regardless of how fast he is. It's easier to swim over people than to have them crawling on your back, punching you, ripping off your goggles and drowning you.
He needs to use the bike to ensure that he is hydrated and has enough gels in him/energy for the run. If he doesn't drink/stuff it in on the bike it will make it harder for him in the run.
Oh yeah, and write a list of everything you need to take so you don't foget anything important - like bike, pump, water bottles, running shoes, swimming goggles etc - it happens.
Hope that helps