I'm pretty sure the letters are cut out of some kind of leather (vinyl?) then applied to the jacket (as opposed to painted on). There are toy skeleton pieces in the first B, the A and Y (the skull is on his slingshot).I'm uncertain where the top of the letters disappear into the fold/collar/hair, but I have a basic template that should work well. I have also attempted to compensate for perspective in my template, but it's not to any particular scale - you'll want to save the image and figure out dimensions relative to your jacket.
I would recommend is 3M's Super 90 spray adhesive. Spray the back of the letters and place carefully. It should hold it for a very, very long time.
