I have a refrigerator in my basement that worked awesome until I tried to do the same thing. I've been planning to get a second refrigerator identical to it, cut out the left wall of one fridge, and the right wall of the other, and bolt them together. So it would be a double-door mini fridge, powered by one fridge. I think a fan on the inside would also be necessary, but I think it would work great for lagering.
"Stop giving me credit for those stupid quotes! For that last time it wasn't me! STFU NOOB!" <-- Benjamin Franklin