How can I get backstage passes to the American Idol "Idols Live" tour?

My friend and I are going to go to the Idols Live tour this summer. We really want to get backstage passes, but I’ve heard they’re not for sale. I’ve also heard that if you get there really early and ask the guards and stuff for backstage passes, they will sometimes give them to you. Does that really work? How can we get backstage tickets?