Type in codes anytime during play: 

CODE                  Effect
LEECH                 Better defesive back
GLOVES                Better catching
BIGFOOT               Better kicking

Special teams
ORRS HEROES           EA SPORTS TEAM
JETSONS               OLD OILERS
GHOST TOWN            WILDWEST
SNAKE                 OLD OAKLAND STADIUM
DANDAMAN              OLD MIAMI DOLPHINS
SHARKSFIN             TIBURAN SPORTS COMPLEX