Truck Forums - snowplow package/roof lamp provision

Truck Forums (https://www.truckforums.com/forum/)

- Chevy Silverado/ GMC Sierra Forum (https://www.truckforums.com/forum/chevy-silverado-gmc-sierra-forum-11/)

- - snowplow package/roof lamp provision (https://www.truckforums.com/forum/chevy-silverado-gmc-sierra-forum-11/snowplow-package-roof-lamp-provision-13100/)

snowplow package/roof lamp provision

Just bought 2010 K-1500 with snowplow package and "roof lamp provision". I know where the switch is but no idea on the process to wire a light on top.
No one can tell me (not even dealer) how to access the roof wiring and how to install emergency light on roof. Can not find any installation instructions from GM. How do I get to wiring and also remove ceiling to put in bolts to hold light. Worried since truck has side air bag curtains. Can anyone help me out? Seems like there must be an easy way but I do not know it.

The wiring for the provision lamp is tape to the roof behind the headliner. Usually there is a relay in the left rear "c" pillar for that system.