I did the same thing to my SC shortly after I bought it.
Yes, remove the door panels and remove the two nuts that secure the handle from inside the door. (a flashlight is handy) then from the outside, remove the little "sticky pad cover sheet thingie" (techincal term
) on the handle guard and press it onto the recessed area. Then it's just a matter of putting everything back together. I like the way they look and definately like the way they keep the paint from getting scratched or covering already scratched paint.
I also did the stone guards on my car.
I hope you bought the guards for the SC/Carrera and not the 930 guards. I've seen people put turbo guards on narrow bodied cars and it just dosen't look right. Anyway, I pulled back the rubber rocker trim and carefully trial fitted the guard. I eye balled it to where it looked best mainly keeping in mind the rear edge in relationship with the forward part of the wheel well. (There is some extra material that will be covered by the rocker trim) Then I used a white grease pencil to make a couple marks for fitment as I held it in place with the backing still on. There should be a bit of extra material at the bottom of the gaurd... I cut a bit off to use for the torsion bar cover. I used a piece of heavy paper to cut the rounded piece by trial and error. Once I was happy with it I just traced it onto the small piece of material I previously cut off. Only a little bit of the torsion bar shows on my SC. Your Carrera has much larger ones. You might have to do it a bit different because of this. I love the way they look (classic Porsche) and I have noticed a few very small nicks that would have been a sizable chip in the paint if it weren't for the guards.
If you have any other questions feel free to ask.
------------------
Leland Pate
___79 SC Targa