You know, theoretically it would be possible to bust into the control system of the fridge and alter it. When you turn the temp selection dial on the fridge you are probably turning a potentiometer, or variable resistor to a more or less resistance level. The trick would be to measure the max and min resistances of the potentiometer. if the max resistance is the warmest fridge setting all you would need to do was to solder a two cent resistor, or even another five cent tuning pot in series with the factory's in order to effectivly double the highest temperature of the fridge. Keep in mind though the maximum temperature of the fridge would be the ambient temperature where it sits; no heating devices are present.
It might be a little more complicated, but I'm pretty sure fridges run on comparitor circuits with schmitt triggers; I am after all an unemployed recently graduated electrical engineer. Anyone in the greater Seattle area want to donate a fridge for the sake of science? I've been searching for the exact quality unit which fills all my stringent requirements, ie free, for the last few months.
Optimaly I would like it to be able to be set for between about 40 and 70 Deg F. assuming ambient is above.