How do you get idolized by the brotherhood of steel

Because you said "idolized" I'm assuming that you mean Fallout: New Vegas. If you get into the underground bunker of their's in hidden valley (can be done different ways), you should ask around. Talk to a few people and I'm sure you can find something to do for them that will make them like you and the more you do, the bigger assignments they give you, the more caps and the more they like you :)