Here you go:
1. Power OFF
While pressing [AE-L]+[INFO], turn the camera on.
Firmware is desplayed on LCD.
Press [MENU]->[MENU]->[INFO] within 5 seconds.
You can see DEBUG mode screen.
Press [MENU] to bring up the menu
By pressing [Right key],Make [DEBUG MODE DIS] to [DEBUG MODE EN].
Then, Press [OK].
2. Press [MENU], then get to the Setup menu.
By pressing [Up key], select AF TEST.
By pressing [Right key], go into AF TEST menu.
By pressing [Down key], select FOCUS CORR.
now you can adjust shift amount by pressing [right key] or [left key].
(*Don't touch AF Area Test.)
Add value for back focusing, minus for front focusing
after changing the value, Press [OK] to save.
3. Test your camera that Focus is corrected.
(repeat step 2. till you are satisfied w/ the result.)
RETURN TO NORMAL MODE:
4. Power OFF
While pressing [AE-L]+[INFO], turn the camera on.
Firmware is desplayed on LCD.
Press [MENU]->[MENU]->[INFO] within 5 seconds.
You can see DEBUG mode screen.
Press [MENU] to bring up the menu
By pressing [Right key],Make [DEBUG MODE EN] to [DEBUG MODE DIS].
Then, Press [OK].
It shoud work
I guess I've been getting in and out of debug mode so frequently, I can change an AF value in a matter of seconds (on Ds, DL, K100D)