I am sure this would need an experienced technician to perform the calibration. But, doesn't this problem can be solved by adjusting the "regulator correction device" as shown in photo?
"A regulator correction changes the effective spring length of the oscillation system’s hairspring. Before the hairspring hits its outer fixture point it passes through a gap formed by two adjacent pins. The part of the spring between the gap and the outer fixture point is exempted from the free oscillation of the spring. If the position of the gap is shifted by a regulator correction, this changes the active spring length. Depending on the direction of the change, the watch then runs faster or slower."
Also see: http://www.sinn.de/en/Technology_Glossary.htm