LOS ANGELES (Reuters) - Aerosmith song-writing duo Steven Tyler and Joe Perry headline this year's class of inductees into the Songwriters Hall of Fame, the organization said on Friday. Singer Tyler and guitarist Perry wrote such rock classics as "Dream On," "Walk This Way" and "Love in an Elevator" since the band formed in 1970 and went on to win four Grammy awards. Aerosmith was inducted into the Rock and Roll Hall of Fame in 2001. ...