After enough practice I can do this now without hassle and just using my fingers.
You position the clip with the centre nose just on top of the metal bracket. Then you push the lower end of the clip into its place at the pad whilst holding the center plate firmly in place. Then you repeat with the upper end of the clip. At this point the lower end pops out. You repeat again, all the time keeping pressure on the centre plate, and this time it will be closer before the other end pops out. After one or two iterations of this both ends are in, with a couple of millimeters of purchase on the pads. Now you use both hand to push and move the centre plate so that the nose pops into the bracket, done. It always takes a couple of iterations but it also always works. I just did it replacing with brand new full size pads and it was no hassle.
