Guy McElwaine, a founding partner of International Creative Management and one of Hollywood's more respected prototypes for the modern agent-turned-studio boss, died Wednesday after battling pancreatic cancer. He was 71. A former MGM publicist, McElwaine joined ICM in 1975 after his original agency, CMA, merged with Famous Artists; it was his second turn repping talent after handling the likes of a young Steven Spielberg and eventually overseeing worldwide production at Warner Brothers in the early 1970s.