Its very simple. Now my cpu runs at 2160MHz with 667MHz FSB. This was classic pinmod with a wire. I connect in a socked BSEL[0] with BSEL[1]. This mod putting all 2 pins in high state. There is no need to isolate BSEL[1] pin.Others overclockers reports problems wiht multipler stocks at 6x, but in this model of fujitsu i have no problem with this.
I have factory RAM and runs at 667 without problems.
Good luck