I went to the shop that replaced our door openers a couple of years ago and asked about the Homelink programming. I asked about the possible effects on others cars and was told there should be no problem. He did say that if the learn button is held down for 30 seconds or more, it will erase all codes and you'll have to start all over again. Now this is with a Genie opener, don't know if this is true with other brands.
In the link, click on which language you want, then the next page, click on "Programming". Just use the drop down menu for your particular car, then watch the video..it does work. I did just that and got my garage door opener to respond to my Jag., took less than 5 minutes to complete it. Then I checked my wife's car's remote and it still worked just fine. All done..

www.homelink.com

 

That's nice we have a FAQ on the homelink as well