I just finished putting a HAG215 in the car, and I thought THAT was a difficult project. I've had DSS axles in multiple vehicles. I am surprised that they could not adapt it. As for the ABS sensors, I cannot imagine that you will get the ESP to play nice splicing the signal wires in. It might work, but I sincerely doubt it. The ESP is one of the "smarter" modules in the car, and being safety related, it will trip a fault code over the most minor issue. As Mark said, if you do it, make sure to unplug the rear sensors.

Separately, please do post up pics of this swap. This kind of mixing of parts and fabrication is right up my alley, so I'd like to see how you approached it. Thanks!