I just did the coming home and leaving home mod for my A3 based on

cominghomelights - Audi Retrofit

Was the best $19 I ever spent. I dont have auto lights on my A3. But I now have CH and LH lights.

Had to order the part as there was only one in Melbourne, and was $19 from Audi. I rang VW but there were none in Victoria. The wire is double ended, so you basically get 2 for 1. You only need half length so dont be afraid to cut it in half. Part number is now 000 979 009E

To clarify some of the things in the referred URL above.

When they say look up and under, I they mean back up and under, toward the front of the car from the fuse box. You will need a torch to see the letters on the connector block, but for reference, it was the closest to the centre of the car in the second row.

The red locking slider had to move towards the centre of the car, not towards the door to release.

Once you pull the connector out, the actual connector block comes apart. If you look closely, you will see a little catch on the side of the plug, this basically lets the outer casing slide off sideways. It is soooooo... much easier to push the end of the repair wire in, with the casing off. It is also the only way you can see the numbers of the pins.

I counted the pins and had the right ones, but couldnt push the end of the wire in, so once I figured how to remove the casing, it verified I was in the correct pin, and the end of the wire slid straight in. Then slide the outer casing back on.

I used a different ground point, closer to the front of the car, just to the right of the fuse panel.

Once all back together, I set with VCDS, and then also found a setting to enable CH and LH in the MFD.
Change Byte 15, Bit 7 to 1, in central electrics

Now I can change the times with out using VCDS as well.

Tools needed aside from VCDS. Flat screw driver to get fuse cover off, Wire cutter (long nose pliers), 8mm socket wrench, 10mm Socket wrench (used for different ground placement), something to strip end of wire with (I used a stanley knife as I dont have wire strippers), small flat screwdriver to prise retaining clip on connector block.

Time taken without stuffing around < 30mns.

I would post pics, but I have trouble with this on the forum.