i just depends on what you have for a button. if its the vinyl one then all you do is simply clean the area with rubbing alcohol or what ever you want. then get a small bowl fill it up with cool water. and a drop of soap. people say johnsons baby soap is the best. i don't really care. dawn works the same for me.
then place it over the horn button plastic and all. you'll want to center it the best you can. then heat shrink it to your horn button. you can use a heat gun or a blow dryer. what ever you prefer.
when it starts to shrink you can pull the heat away and work out all the bubbles/wrinkles for a smooth finish. make sure there's no dirt before you lay it down. its actually pretty simple and not complicated.
if you haven't ordered one yet i'd recommend this guy at this site. http://home.comcast.net/~rsvinylgraphics/rsvg.htm
his email is firstname.lastname@example.org
he's a great guy to deal with. and awesome prices.
Hey bob, quick question. I heard from rick that you may have done the Trd horn button switch and I was wondering how do you remove the clear plastic button off and does the Toyota logo come off too or do u have to peel it off from the button or do u just paste the new sticker over it and then the clear button over the new sticker