The drilling points are marked with a spring-loaded center punch. It’s hard to see in the picture but the marks are there.
Now the mounting holes are drilled, first with a small pilot drill, then the bit of the proper diameter.
Here are the drilled holes ready for the bar installation.
The templates for cutting the B pillar finishers are put in place.
The template cut lines are drawn on the finishers with a Sharpie.
An air saw is used to cut out the hole in the finisher for the harness bar to fit through.