So for anyone installing the mud flaps, a few tips from my experience:
For the rear ones you WILL need to remove the entire plastic wheel well in order to put the metal screw retaining clips onto the holes in the bumper. From memory there are four Philips head screws (three of them on the bottom) and two plastic plugs on each side, plus a strangely shaped large plastic nut on only the right (passenger) side. Once these are removed, just pull the plastic toward the inside of the car to remove it.
The front is much simpler, you need only take out the three plastic clips on the front of the plastic panel to enable you to reach inside the rocker panel to push the rubber hole plug out of the bottom.
I'll post some pictures later, but hopefully this helps some to anyone who is working on it.