I ran into your post as I was looking for the instructions on how to do exactly that. turns out I had them but lost them and need them as well.
So I messed around and figured it out on my own, so here is the procedure
Unplug the control box.
open the control box and locate the two dip switches on the back side of the circuit board.
in 'run' position, both dip switches should be depressed on the hinge side of the switch (hinge of the control box door).
Flip both switches to the outside.
remove the thermocouple from the mash tun and plug it into the control unit.
close the control box and plug in.
turn the power on and you should see 50.0 degrees on the temp set side and -- on the time side LED displays.
Press the temp set button one time, and the time side will display 'LO'.
Insert the thermocouple into a glass of ice water and stir it around until the temperature stabilizes...it may not be 32 degrees, mine settled at 34.6 today.
Press the temperature set button once more.
The time display will show, 'HI'.
Now put the thermocouple in a pan of boiling water and keep it there until the temperature stabilizes, again it may not be 212, mine settled in at 214.5 today.
(in both cases the lo and hi portion of the work, the stabilized temp will still go up and down a few tenths of a degree, but what you are watching for is the temp to stop going down with the ice and stop going up with the boiling water)
Now press the temp control again and it will say 'CL' which means 'calibrate'.
Press the temp control one more time and it returns to '--'.
Turn the power off.
open the control box and set both dip switches back to the run position (lowered on the hinge side of the door).
Now you can test the temp reading by using the ice and boiling water again to verify that your system is reading properly.
(mine read ice water as 31.8 degrees and boiling water as 213.1, close enough as the system is really intended to be most accurate at the mash temps around 150 degrees.)
hope this helps.