I have dewipered my car today.
It is really simple.
Remove the two side trims off either side of the boot by unscrewing the two screws that secure them in.
Then unscrew the screw in the tailgate handle.
Gently pull away the plastic trim, don't worry if it cracks and bangs, its ok
You will then be left with all the motor and wiring showing.
There are three bolts holding the motor in, unscrew these and gently separate the wiper from the motor.
I used two grommets, one inner and one outer.
Inner is a 19mm grommet
Outer is 24mm grommet, but im currently looking for a better one.
Hope this helps?