I do the pinning thing too, but I use styrene rod (available in very small diameters) instead of a metallic pin. Pin the part (mirror, etc.) using CA or solvent-based cement and paint it if need be; after the body is painted, drill a hole for the pin, put a dab of medium CA in/around the hole, and attach the part. The medium CA allows you a brief "work time" to ensure the positioning is correct.