Has anyone retrofitted the Homelink Garage opener? What is invloved?

I'm talking about in the C5 which had the Homelink in the sunvisor? The newer models seem to have a transmitter behind the bumper and somesort of module in the dome.

 

I found this article. I hope it is as simple as this:

http://www.audiworld.com/tech/elec19.shtml

 

What is the advantage of upgrading the homelink already in your car?

 

Actually the car didn't come with homelink and hence I wanted to retrofit it. From the article it seems that the homelink system is completely integrated into the sunvisor, so it should work.