Enter the snooker room and use explore mode to look at the stool. This should take you into a mouse hole. Look around to see the "Cheat Mode Activated" message. You can now play against all characters.

Go to the icon that lets you walk around in the snooker room look at the grandfathers clock and behind it is a mouse hole then look for the cheese and then it will save to your VMU

Just before Jimmy takes a shot, change the shot speed to the lowest setting and he will miss, giving you control of the game.