Whilst not strictly a VCDS mod par se, I'm going to give this mod a go probably over Christmas when I'm next off. It's replacing the lower door red reflectors with proper active lights.
I did this mod in my previous Scirocco and all I needed to do was buy the light modules, some repair wires and 2 connectors from VW parts department (think the whole thing came to £20 ish). Just 2 wires from the lights need to be fed into the door control module, then adding them into the door module coding using VCDS. They look like this when done (this is my old Scirocco). As it happens, I removed the units from the Scirocco before part exchanging it, so I still have them in the garage.I've done a dry run, and the light units fit perfectly, and the red reflectors part number is exactly the same as the Scirocco / Golf 5 and Golf 6.
Door Light by
Sootchucker, on Flickr
Now the new Audi A3 (8V), doesn't come with reflectors, but instead active door lights. I've checked ETKA and the circuit diagrams for both the A3 (8V) and the Golf 7 (5P), and they seem to share the same module, it's just that VW have decided not to use the door warning lights at all. Checking the diagram, Terminal 16 of the 32pin connector is the one that sends power to the door lights. It's wired up on the A3 but left empty on the Golf. The negative is the shared negative that the whole door module uses.
When I get round to doing it, I'll post up more photos and a how to for everyone. I know some people will say it's not needed because of the ambient lighting, but being illuminated red straight on, and white light straight down, really makes the door stand out at night and provides quite a bit of additional floor illumination at the rear of the door area.