The first time I did it, I pressed the first and third button until the home link light stays solid.
Then I pressed and held down on the first homelink button (or which even button you want). At the same time I held up the garage remote next to the homelink system, press and continue holding until the homelink light blinks faster.
I found this tutorial much easier to work with than the Audi ones.
[video=youtube;mvoKBm7h3aY]https://www.youtube.com/watch?v=mvoKBm7h3aY[/video]