I have put a 722.6 with Ole controller into a 560SEC and I believe it was very straight forward. It took me less than two days to do the wiring for the controller - install, connect to ABS sensor and throttle position sensor. Getting the wires through the firewall was the hardest. I installed the Ole controller on top of the airbag module (the ashtray is not functional anymore). Configuring the Ole controller is pretty straight forward and I got the car to run well in half a day. Initial set-up is simple. You calibrate the throttle position and driving speed, adjust the overall shift hardness, and set the throttle position % for downshift, select your type of engine and decide when you what the torque converter to lock. I might have forgotten something, and there is certainly more, but with this you will be in a great position already, and the driving improvement is very obvious. You don't have to shorten the drive shaft either.
I got my transmission from Sun Valley Transmissions in LA, even though I live in Florida as they were recommended a lot; Marc is great and the transmission is top notch and pricing is very fair. For the M119, it is a direct fit as far as I know. For the M117, Marc puts in an extra pin / bolt.
Again, to me this is a great improvement and you can even paddle-shift the transmission if you like. If I buy another car with a 4-speed auto, I will do it again.