When you enter the diving contest try to select the moves that only use a couple of buttons (eg. Backwards 3.5 Sumersault Tuck- degree of diffuculty 3.4). It is a hard dive but only needs the X button and then the O button at the end, simple!
At the Main Menu, press Left, Left, Right, Right, Up, Down, Left, Right, Left. If done correctly, you will hear a sound. Then select Olympic mode.
First in All Events:
At the Main Menu, press Triangle, Square, Circle, Square, X.
At the Main Menu, press Circle, X, Triangle, Square.
Gold in Sprint Event:
At the Event Selection screen, press X, X, X, Circle, X, X, X.
Gold in Javelin Event:
At the Event Selection screen, press Circle, Square, X, X.
Thanks to Revolution readers Phoenix, lew and Carl!