To program the keyless remote entry fob on a 1999 Audi A6:
1) Insert Key 1 into ignition and tun on all but ignition.
2) Shut door, Insert Key 2 into driver side door.
-Turn Key to lock door
-Press unlock button once: lights blink
-Wait 10 sec
-Press unlock button again to program that remote: lights blink again
3) Remove key 2
4) Remove key 1 from ignition.
Thank you so much for posting these instructions, it worked like a charm.