You fill it from the drain hole with a special tool. To do the job correctly, you also need a VAG-COM scan tool to verify that you're topping off the transmission fluid with the transmission at the correct (operating) temperature.
In other words, this isn't something I would do myself, and it's certainly not something I'd ever trust a "quick-lube" shop to do. But then, I don't even trust a "quick-lube" shop to properly change the oil in a car after watching them tell a friend of mine to start his car, only to find out that they'd forgotten to refill the engine with oil! He was really mad that day.
It's not that hard and the trans fluid temperature is not that critical.
Here is the deal, the trans temperature needs to be above room temperature. You do not need VCDS to see the trans temperature, the Android App Torque Pro will display trans temperature for under $20 with the interface. You can also use an IR thermometer or just use the palm method. Put your palm on the trans pan, it should be warm but not too hot you cannot keep your palm on the trans pan. The upper fluid temp limit is so you do not get burned when hot fluid leaks back out the underside fill port!
Anyway, see this link here for fluid fill info and tools, no special tools needed, just a tool that works/fits the drain pan.