Here is how I did mine gauge pod:
Drilled Holes
Cut with Dremel to fit
{no pics here, sorry}
Constantly checking fit on Pillar
{refer to third pic}
Aline gap between gauges protrusions with hole:
Test fit pod to pillar to see fit again:
What should have happened next:
Cut hole for passing vacuum line and light wires in A pillar
Glue pod to pillar with amazing goop marine/rv/automotive/plumber/any really. (needs to be a glue that is flexible enough to fix plastics)
Attach wires to dimmer switch
attach vacuum line to manifold (somewhere close to the intake runners is preferable)
Reinstall trim in car
Enjoy!
And other gauge pods I made turned: