Use a text editor such as notepad to edit the "defuser.ini" file in the "\ea games\harry potter and the prisoner of azkaban(tm)\system\" folder. Find a key that you want to use to turn on Ghost mode, such as "Backspace=". Then, add "Ghost" after the key and the equals sign, so it appears as "Backspace=Ghost". You must also select an alternate key and type "Walk" after the equals sign. Press the key that was assigned during game play to turn on Ghost mode. You can walk through walls and fly. You must press the key assigned to "Walk" to fall to the ground.