Well... NOT ANYMORE!!! I finally got around to installing the ductwork so I can now use the vent.
Step 1: Drill a small pilot hole all the way through your wall. For this you'll need a very long drill bit - about a 12" x 1/4" bit is what I have. Determine the center of your duct on the inside of your cabinet and then proceed to drill a hole all the way through your wall. I know, it's a little unnerving. Make sure you hold the drill perfectly perpendicular to the wall otherwise the hole you cut on the outside will not line up properly with the hole you cut on the inside.
I got lucky and set my circular saw depth perfectly on the first try (3/4"). It cut all the way through the siding, but left the tar paper untouched underneath.
Step 4: Cut a hole through the back of your cabinet and the interior wall. Use the same method as you did on the exterior. If you took your time, measured right, and are an expert with the saw, your holes will line up perfectly and will be about 1/4" bigger than the duct. If you are like me, it will be a jagged mess that needs trimming until you can force the ductwork through without too much bending and warping.