I have a spare normal keyboard for my L702x so I decided to try removing the palm rest to fit it just to see how easy it was. I read the instructions in the Dell service manual and also found a YouTube video where the guy used a screwdriver to prise off the palm rest but there was no way I was going use a metal screwdriver.
I used a couple of those green plastic case openers and slowly made my way around the palm rest popping it off at each clip and finally it came loose and I was able to replace the keyboard.
So overall it's not that difficult to replace the keyboard but it is a little daunting at first as starting off is a little fiddly and popping the clips can be troublesome when they don't pop right away.