The wiring color scheme is different from the new ones. You must connect/solder white and green wires. Isolate with hot shrink tubing or tape.
In combination with most other pickups, you'll use the L-500's red wire as hot lead. Solder this to the lug where the hot lead from your stock pickup is connected now.
Black and bare wires connects to ground - ie. where the shield from your stock pickup is wired now.
If you get a thin and very trebly sound when both pickups are selected, pickups are out of phase with each other. To cure this, swap the black and red wires from your BL. Bare wire connects to ground in any case.
Good luck.