Of course, there is a special tool.. but. What you need to do is (somehow) machine a cavity that the ring fits snugly into. I did it on the cnc mill, but a lathe or template with router, etc. would do it too.
Once fit into the cavity, take something like a tack puller and "carefully" work around the crimp, picking it up a little and moving around the bezel several times until the instrument can come out. Reinstalling is putting the assembly back into the cavity and taking a flat punch and "carefully" tapping the bezel inward. When moving metal like this, a hundred small pecks is considerably better than one big one..