Thanks to the OP for posting! This saved me the cost of a temp controller so i figure I'd post how I got mine working.
Just bought a GE 7cuft Freezer Model FCM7DUAWW.
Shot of the Thermostat:
I unscrewed the side vent and pushed in the clips to pop out the themostat.
Once the themostat was dangling out I found the set screw. In this pic it's the top screw in that oval on the side.
It took around an entire week to get the temperature set high enough. I first turned freezer to the warmest setting. Then I screwed the set screw in(clockwise) 3 turns, let the temp stabalize over night. Repeated that over several days. Eventually I got to a total of 11 turns and the freezer temperature was sitting at 48 degrees F at the warmest setting. I wanted the temp down around the upper 30's so I put the thermostat back into the freezer and used the front dial, raising the setting up(cooler) little by little to adjust the temp a little cooler. It didn't take much and I got the temp down to 38 degrees F when the dial was at the 1.5 setting.
It takes some time and patience to get the temperature correct since the freezer has to adjust temperature overnight. But if you take your time and let the temp adjust lowering it little by little then it can be done. =)
Goodluck and Cheers!