Would love to hear how it turns out. I just attached this lock to my briefcase project and I was not happy with the results. I'm not very experiences like most of the contributors to this forum, so there might be some glaring rookie mistakes with my method.
However, I would advise you to be careful when cutting the square for the inner lock mechanism. The holes on the plate/backer are VERY close to the lock box. Mark those holes on the leather before cutting the square.
A few thoughts, which might help. As far as I can tell there is no good tutorial for attaching these locks. I tried using Al Stohlman's tip of using #14 burrs with large escutcheon pins, but the burrs were too too big.
-The holes to assemble the plates were too close the the cut square, and barely had any bite in the leather. Not a huge deal since there is a back plate, once attached keeps everything together.
-When peening the escutcheon pins to secure the backplate, I laid thin leather under the pin head to reduce damage. This caused the pins to push back out slightly, and therefore the lock does not sit flush to the face of the case.
-It was difficult to peen the pins because they sit so close to the inner lock mechanism. I had to take great care not to damage the face of the lock. Next time I would probably use a block of wood with a hold drilled the size of the Key latch.
-I'm not sure why, but the lock does not close very well now that I have everything assembled. I cut notches to allow plenty of clearance for the latch bar to move up and down. So i'm not sure what the issues is.
Overall, I'm disappointed with my execution. I hope you have better luck!