It can be done using a right angle screwdriver. Put the Moonroof into the vent position and slide the shade back you can see through the glass panel the two screws that hold the clip on. Remove them. Insert the new clip in the correct orientation and slide it toward the rear of the car allowing the plastic part of the clip to slide between the rail and the fabric liner. Install the two screws. I have done one side in less than 15 min. (most time spent cursing the screws) So it is not that difficult to do with the correct tools.
"It's not because I'm an aggressive driver, it's because I'm an idiot" actual quote from my wife.