Go into the Superstar Hall Of Fame and select a player based on which position you would like to play through, appearance, etc. At this point you are not selecting them, but you know which player to alter. Go into Roster mode, then to the players' team and begin alteration. You can change all the characteristics that let you highlight them as usual. Once you have changed the appearance, etc. go to ratings and adjust them as desired. Go back into Superstar mode and the player you modified will be at the top (if you made them with perfect ratings).