I tried adding the potentiometer to the black temperature wires. After adjusting the knob and testing the results over time, I was successful in offsetting the temperature sensor's voltage. The thermostat was reading 10degF higher than the actual internal temp (eg thermostat reads 45, internal temp would actually be 35). However the compressor was randomly turning off when the internal temp got around 37-38... I found out this was due to the auto-defrost sensor (white wire). Adding another potentiometer to the white wire would solve this issue, but since there is no visual feedback on the thermostat regarding the defrost process, i knew trying to make blind adjustments to another knob would be an agonizing process that I didn't want to deal with.
I ended up cutting out the the internal thermostat circuitry and wired in a PID controller w/relay output using the red/brown/blue wires. I even used the old thermostats housing to hold the new PID controller in the same location as the original. It has been working great and sitting at 35degF with a 2degF hysteresis!
I plan on wiring a fan to the PID's alarm1 terminal and possibly a colored light to the alarm2 terminal (just for looks).