all very simple, fiddly but simple, you just need to make sure that the mechanism you buy is the right size for the thickness of your face. Basically one hole, the mechanism has a shaft which sticks through to the front, there will be a thread on the shaft, onto which you screw a washer and nut (from the front), you might want to secure the mechanism on the back too, but that can just be a blob of hot glue or a simple frame, it only serves to stop the mechanism from spinning if you nut isn't quite tight enough. then you just push the hands into place.