Replace the outside keypad on a 2003 Expedition

So, I found out that my wife simply locked her keys in the truck EVERY DAY that she went to work, and would use the code to get in, and well as you probably guessed the buttons are worn down pretty bad, and are hit and miss.

I would like to replace the pad, I was just wondering what is involved? Do I have to take the whole door apart? At the very top of the door (where the pad is), there is a black plastic piece of trim that the pad buttons come out of. Is there just a simple way to pop that off?

I need to get a repair manual for the truck anyway, but I figured I would ask on here to see what I am going to be getting myself into.