Unlock Codes Entry Screen:
In the "Options" menu select "Game Play". Press and hold D-pad Left AND Left Stick Right (Move the Left stick to the Right) and press Start. The "Codes" selection will now be available at the "Options" menu. 

Unlock NBA 2K2, Sega Sports, and Visual Concepts Teams:
Enter "MEGASTARS" as a case-sensitive code in the "Codes" entry screen. 

Unlock Muhammad Ali and Michael Jackson:
During an exhibition game press Start and hold L. The screen should shake briefly to confirm correct entry. Now MJ and Ali are on the Sixer's starting lineup. 

Airball:
Select "Street" option at the main menu and press White then hold L and press Y, Y. Now press Start and "Airball" will appear to confirm correct code entry.