Aux heater is simple, turn on climate control and warm air comes out the vents. You don't think, you don't program, you don't do anything...it just has an electric heating element in line that gives you early heat until the slow to warmup diesel gets warm enough that the usual heat exchanger method starts to work. If I'm not mistaken it comes on every V6 TDI of every trim level. Kind of essential otherwise you'd have to drive around for 10 mins before getting any heat out of the diesel.
The V10s had a diesel fired heater that could be programmed (there was complexity in getting the programmer installed etc). Worked amazing well, people wondered why exhaust fumes would come out of the drivers side wheel well, and I'm sure it wasn't environmentally friendly - but it worked and was interesting.