I use the Op-Tech system for several of my cameras--the neck strap combined with different lanyards. For the longest time, I was trying to insert the plastic retaining clip into the body of the mount (type B) until I discovered this simple trick:

THE LANYARD BODY WILL SNAP ONTO THE POST WITH THE RETAINING CLIP IN PLACE!

Of course to remove the clip and lanyard, it is necessary to pull the plastic clip out and lever the snap plate up. I tried this with an "A" mount also, and it was the same deal. Sometimes, I think we make things harder than what they need to be...