im in the same predicament m8 wiring mine upto the headlight switch

presuming you can multi meter the cables to find the switched live?
had this for my boost gauge if any use
For Constant On Gauge Backlighting:
Switched 12V: Red and Green gauge wires to the Black/Purple
headlight switch wire at position 4.
Constant 12V: White gauge wire to the Red/White headlight
switch wire at position 8.
Ground: Black gauge wire to the Brown headlight switch wire
at position 6.
For Dimmer Knob Controlled Gauge Backlighting:
Switched 12V: Red gauge wire to the Black/Purple headlight
switch wire at position 4.
Dimmer Control: Green gauge wire to gray headlight switch
wire at position 10.
Constant 12V: White gauge wire to the Red/White headlight
switch wire at position 8.
Ground: Black gauge wire to the Brown headlight switch wire
at position 6.