Just stick a small screwdriver slightly bigger than the opening through the washer. It will spread it out just enough to go on the pin all the way without breaking them. I used a small deep socket as well to help evenly push the washer on.
This is the one I got. It uses the locking washers to keep it in place!
http://www.cjponyparts.com/ford-grille-emblem-running-pony-black-2015-2017/p/GO35/