(8-19: Updated with more details and exact instructions of mine - There is a major error (intentional?) in the Pentax Hack for their told operation procedure to make it works, just read more carefully below if you want to "risk"! It does work! ;-))
Here the new excellent Russian Pentax DSLR hack site strikes again! They have posted the simplest method/hack (ever!) to enter the debug mode of various Pentax and Samsung DSLRs, namely, the K10D/GX-10 (FW 1.10), K20D/GX-20, K200D, K-m and K-7!
http://www.pentax-hack.info/documents/blog.php?entry_id=1249616275
So, what you need to do is just to create a text file named as"MODSET.XXX" that is to copied to the root directory of your SD card. In that file, just type the command line(s) that you wish to be executed (by pressing the DELETE (NOT MENU) button while turning on the camera). To enter the Debug Mode, the MODSET.XXX file only needs to have the following line (for my K-m, it is named as MODSET.464):-
[DEBUG_MODE EN]
The camera has now been put into the Debug Mode, the Debug Mode Menu with Sub-menu items will appear forever until another command is executed to tell the camera to get out of the Debug Mode (will tell you how to do it in the next paragraph). Next, press the MENU button again, then the Debug Mode menu tab will appear and can be found between the original Set-up menu tab no. 3 and the Custom Setting menu tab no. 1. The new tab is just named "Set-up". To do AF adjustment, just go into the "AF TEST" sub-menu and then under which enter the "FocusCorr" value (in um). The default value of the FocusCorr is 0 um.
To Turn Off the Debug Mode, simply modify the command line(s) in the same file to and repeat the above procedure:-
[DEBUG_MODE DIS]
Enjoy and happy hacking! This "feature" is particular valuable for those Pentax models without any focus adjustment feature, like the K200D and the K-m.
As a general Reminder and Warning: Do all these hacking and entering the Debug Mode at your own risk. If you don't know what you are doing, my recommendation is that you should not try it! :-)
I have successfully entered the Debug Mode and change some settings (but reset to defaults afterwards), Screen Captures of the Debug Mode Menus and Displays of the K-m is to follow!! (Hopefully within this week - I shall see if I have the time to do it :-))
Update: The K-m Debug Mode Screen Captures can be found Here!