At the main screen, choose Team Management, then click on Customize. Click on the name of a player and type these codes. Press enter after inputting, then click again and type another code:
World Cup '98
Zico Enable 1982 Classic Match HurstEnable '82,'74,'70,'66 Classic Match KennyFlaming Ball GaboBig heads KyleSkeleton players CartmanTake a dive GonzoHot potato Mr HatCrazy Ball PowderSilly Moves NeilaAlien Mode
Press 'back' to exit without actually changing the players' names. Now press Scroll Lock to open the cheat menu.
Thanks to Revolution readers Kajan, Rahul and Gaurav, Marco Ulivieri, and Paul Gordon!