Maybe I'm bit late, but here is the answer:
Your first steps are the right one (with the files on the sd-card and door open)
* You see "Development Menu1" at the screen after turning on the camera
* at "DEBUG MODE" click "right", then it switched to <EN>
* now press OK
* screen is going black
* turn camera off
* close the door
* turn on camera again
* now you see "Development Menu1" again
* press MENU to Cancel
* screen is going black
* press MENU egain
* now switch through the settings
* you will find "TEST MODE" and there you can edit your AF-System
* after all is done --> DEBUG MODE DISABLE
thats all