Just like FIFA98:RTWC, change the players' name to one of the cheat codes and press enter. After entering all the cheat codes, press back to undo the changes so that player's real name is not changed. Now go back to the main menu and press Scroll lock to activate the cheat menu.
Zico = Enable 1982 Classic Match
Hurst = Enable '82,'74,'70,'66 Classic Match
Kenny = Flaming Ball
Gabo = Big heads
Kyle = Skeleton players
Cartman = Take a dive
Gonzo = Hot potato
Mr Hat = Crazy Ball
Powder = Silly Moves
Neila = Alien Mode