You can read about the modification
here. It is quite involved, and I'm hesitant to provide any more than a general overview. In-fact, the list of resources is substantial and the risk moderately high.
Some improvements are on the go as we speak. I'll post at a later date.
For now the mod consistently cools 34C below ambient and can be cooled to a set point temperature through the Arduino hardware/software.
DeltaT can be increased by use of a less conductive and better insulated heat sink mounting plate, which is sucking energy out of the system - 3mm acrylic should be sufficiently non-conductive and isolate cooling to the cold finger only.
Here's another little project using an Arduino to control a lens attachment that I use to take calibration frames - it illuminates for flat frames. The sequence is automatic. Screw it on, flick the switch and let it do its thing - go to bed and in the morning, nicely baked bias, dark and flat frames.