I actually have no reason to be posting this becuz i have no idea how to do this since i have the PS2 version....i am actually kind of bored .... but i will ask around and try to help you out if no one else does first
If you have already installed th EA Graph editor then open a file in your NBA live 2003/render folder. The file is named as xplrcmn. Just open it with EAGE and then you will see a whole lotta list to choose from skins, shoes, courts, balls etc.