Look on some European shops and tuning websites, they sell a ready built loom for your 7.5 upgrade from a 6.8.x or 7.1.
My question is why do you want a 7.5 in there? Most 7.5 people end up tuning the drive by wire to work like a cable throttle, mimicking a cable throttle on the AGU, if your not going to use traction control then that's no different than a 3.8.x unit... only real advantage is VVT if your going to add that in. The stuff you want you can be map out. Can even map out additional Lambda sensor and EGT sensor and so on.
Only thing that the ME7.5 will really give you is VVT and Launch control, but launch control is a bit of a gimmick, as all it does is at a given rpm it will apply a load so you can launch of at full capacity, problem with this is, if the tires are better or worse than the launch control you won't get full potential and again same applies to wet/damp conditions, its not like your car knows what your tires are capable of or what the road conditions are.
Variable valve timing is VVT, it can be fitted to earlier 1.8T engines going by the vag catalogue as I was planning to get a AGU engine and breed it with a TT with a BAM engine, except just use the AGU engine with VVT in the TT with quattro on a 7.5 loom.