[Icom] Pointers on getting through firewall?

[WA9ALS - John]

Starting on my mobile installation - biggest challenge will be the power
cable.  Anyone have any pointers, photos, web sites - anything to calm my
fears of drilling a hole in my firewall?

I've inspected under the hood and under the dash and see no usable existing
points of passage.  I'm not in a big city, so taking it to the corner
stereo-installer isn't a great option.

Any specific suggestions greatly appreciated!  (Suburban)  73 - John