Certainly not an "expert", and try to keep things simple... I place the butt piece on the side of a work bench, make sure the tang is level, and drill by hand. The butt part of the piece rests against the edge of the table and prevents it from spinning or riding up the drill. After the hole is counter sunk, the butt piece is screwed onto the stock, and the second hole drilled while attached to the stock.
If the butt piece has a hole for a box release, I attach it to a jig made of 2X4, and drill with a drill press.
I have drilled screw holes in a butt piece with a drill press, by clamping it to a piece of larger wood stock, like a 4x4. I use short parallel clamps to secure the butt piece to the wood, then clamp the wood in the drill press vise. Hope that helps.....
Ed