It is possible to play as a - NBA Live 2003
It is possible to play as a number of other characters in addition to the standard ones available.
Firstly go to the create a player screen and enter one of the codes listed below as your name for the corresponding player.
After you complete any of the codes listed below you will find your new player in the free agent pool. Just select the "Sign/Release Player" option to get him on your team.