Question about moving aux-in to dash.

Hello, new 3G TL owner here, just picked up an '07 base MRP (non-navi). Absolutely love it, runs great, and no problems other than failing hood struts which seems like a very easy and cheap fix.

Obligatory pics:




Anyway, I have a question about relocating the aux-in to the dash in order to use a Mountek phone mount without having ugly cables running down the middle of the car. I have a pretty good idea of what I want to do, just need clarification on one aspect of the install.
My plan is to run an aux cable from the armrest, under the driver side silver trim piece, and out near the audio unit.

I will make a small hole in the trim for the cable to hook into my phone here:


Relocated aux-in:


My main question is whether I will be able to drill through the inside of the armrest to run the cable directly under the trim piece here:


I don't want to hit any wires or screws which may be hiding in there, and I have searched for anyone doing something similar and have been unable to find any info or pics. Any help would be greatly appreciated, this site has already been an excellent resource.