If you want to pin them, just push a straight pin through the wood till you hit the hinge, then push it in until it just breaks through the hinge.

Now, cut the pin off with a pair of side cutters and (using the face of the side cutter) push whatever is left of the pin flush with the stab.

Now the hinge is pinned and all that shows is a pinhole (On the bottom so even that doesn't show)