I have a Challenger and agree with Matt there. I carry strapping tape as part of my repair kit. Use the kind that has the strings in it. You can start by applying them in long strips lengthwise on the underside of the wing. I was under the impression the Xtreme had a carbon fiber rod in it for reinforcement...so the tape might be redundant. But I use it on my AB Challenger and watch with joy as I pull loops and the wing doesn't fold. Also follow Matt's instructions on the wing repair. I have to say that I wouldn't have recommended the Xtreme as a first plane. That huge wing could prove unstable in decent winds. Plus I imagine that plane cruises even faster than the AB with that faster motor. Remember, altitude is your friend. Cruise @ slower speeds and perhaps stick to belly landings and hand launches until you are comfortable with the plane. These are much easier to handle and if you land in the grass...much softer and a little less concern over lining up your landings. I'm not sure the AB Challenger would be discontinued for a while...plus parts should be around for a long time as well. The Firebird has been around for quite sometime and you can still get parts for it even though HobbyZone moved onto the Firebird II and XL.
Just tell him to take 'er slow and steady and not try too many ROG (rise off ground) takeoffs or landings for a while until he gets good at bellying her in. Smooth and steady......
now where did I put that strapping tape?!