From a cappella to habeas corpus : Stephen S. Trott, ex-Los Angeles deputy district attorney and the U.S. attorney in California's central district, has been promoted to associate attorney general, the No. 3 spot in the Justice Department. In announcing the nomination, the entertainment-conscious White House noted that among Trott's accomplishments is a gold record. As a member of the folk group the Highwaymen--no criminal intent implied--Trott sang and strummed guitar to "Michael, Row the Boat Ashore," a No. 1 song in 1961. Not among the Highwaymen's hits, and just as well for Trott's career, was "Birmingham Jail."