The problem with sliding the Autometer pod all the way down is that doing so covers up two of the three screws that attach the trim piece to the pillar, so there's no way to sturdily mount the trim piece if you attach the pods to it first.
What I did was clamp the pod to where I wanted it on the trim piece, then I drilled four holes straight through the pod and trim. I inserted a machine screw through each hole, and put a nut on the trim-side of the machine screw. Then I tightened the screws so they were soley responsible for holding the pod to the trim.
I then JB welded the nuts to the backside of the trim piece. After the JB Weld dries, it allowed for the removal and reinstallation of the pod from the trim piece seperately.
So I install the trim piece with all three screws, then I install the pod seperately.