To keep from causing the stock from cracking and splintering only cut it half way through on one side then flip it over and meet the cut from the other side. The splintering happens as the blade exits the opposite side of the wood.

As for the butt pad they showed this on Midway's tips last night on the Outdoor Channel. Put the pad on the gun and trace the outline then use a grinder or sander to trim it out. put it back on and finish up by hand.