Phil, the snaps do indeed go through the hell of the boot. Here's a pic of mine to help illustrate
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I used long shank snaps on the boot heels, then attached the dome part to the elastic. The elastic is then looped around the boot so it fits snug, but not too snug as you want it to give some without flopping around as you walk. I then riveted the strap to the boot armour ( just make sure that you back the snaps and rivets so that they won't pull through the elastic strap ).