Its pretty easy to remove the S&M gear off the base body, the metal chain is attached to clips and can be removed, the black paints are glued on but the glue is not that strong so you can pull them off pretty easy, then its all about getting it on the Phicen body. You know how getting clothing on those Phicen bodies can be a real pain? Well getting the costume on was a real pain!
It was just a case of inching the costume on little by little, start over the legs and up the torso. It took me about 2 hours to do, didn't want to rush it and break the costume. My advice would be to do it over a dark surface, so if any of the little silver buttons drop off you can see them easier, as you said extra buttons would of been a good idea, only a couple dropped of when I was doing the body swap and I just glued them back in place.