According to Myth Busters, they can just have a someone on the ground tell a passenger how to switch on the automatic landing system!
They tried having non pilots land commercial airlines on last night's episode, with a NASA flight simulator standing in for he real thing. First they tried it with no guidance. Jamie didn't do too badly, I mean he got all the wreckage and bodies inside the perimeter fence of the airport. Adam was still miles away from the airport when he crashed.
With a flight instructor talking to them over the radio, Jamie landed fine, and Adam's plane was salvageable -- if the fire department was on the ball.
Afterwords the instructor showed them how to switch from the Automatic Pilot to the Automatic Landing System.
They left out one big thing in that episode: What to do when things go wrong with the airplane.
Here only years of experience and training will save you. The advantages of youth like strength and agility don't mean so much. That's why I like my pilots to have gray hair.