Bought some diamond bits for my Dremel to do the holes in seat tube, bars and steerer. Had to use a bit shaped like a sharply tapered cone with a little ball on the end to soften the inside corner of the hole enough to be able to drag the wire through - no poking it through when the steerer's inside the head tube.
These holes are about 1.8mm.
Repurposed charger plug, with most of the bulk hacked off it
Ditto for the jack. This had an O-ring on it... when I took it off the jack, I expected it to be a normal O-ring, but nope. Square. Shimano doesn't take any shortcuts; the EW50 wires I hacked up for the plugs are that expensive because they're the toughest wires anywhere near that size I've ever stripped.
