Here in the UK we are able to switch the lights off and on with this switch. I've copied the connections from the wiring diagram:
Sorry it's not very clear, but hopefully clear enough to understand.
The light switch (5) obtains switched +12V from pin 9 red/black wire (rt/sw). This is the same supply as the brake switch (9 on the diagram).
When the switch is in the 'P' position, power is connected to pin 1 black/white wire (sw/ws), and when in 'H' position it is also connected to pin 3 white wire (ws).
Hope this helps,
Norman