Many moons ago I fitted a swivelling towbar to my D4. My lasting memory was the degree of contortion required through the process, both for the bolts mentioned and of course, getting the wiring into the fusebox which was far from comfortable.
Coding wise, I used VCDS, logically going through each module and adding the towing byte, assisted by the Kufatec instructions. It worked a charm until it went in to the dealer next when they reset everything and lit the dash like a Christmas tree! As I was on good terms with them, they fixed this by adding the factory PR code on their system and resetting again.....
As for a pre-facelift on a post=facelift car - I can't say for sure, but I do have a facelift ECU in the garage somewhere, although no-longer have a D4
