More information would be nice
, but I'll make some assumptions.
If you are installing a switch in the center trim panel, under the HVAC, there is a brown wire going into the gray 12-pin connector on terminal K. This connector plugs into the HVAC control head.
It is switched hot by the BCM through the HVAC relay.
I'm also assuming you just need this for an ignition On trigger wire, and the actual power for the lights will be coming from the battery, through a relay.