Go to "My Madden" then to "Rosters". Go to "Player Management" and go to "NFL Greats". Release whoever desired. Then, go to "Free Agents" and put the desired player on a team. When you start Superstar mode, go to play as a rookie and find your player. If you selected a great, he should be close to the top. This also works if you create a player. When you create a player and put him on a team, he is a rookie. When you go to Superstar mode he should also be there.