Sorry for conjuring an old thread but this was really helpful and I wanted to share a tip I found wiring my own:
For those without a wire fishing tool, you can work the cable under the B pillar trim in step 8 from the side.
(1) Run the cable along the trim piece.
(2) Work it just under the edge. It'll feel like there's not much room to fit it under there but there's just enough.
(3) Once the entire run is underneath you can grab it at both ends and gently work it up and over the wire bundle with a "flossing" motion.
For those without a wire fishing tool, you can work the cable under the B pillar trim in step 8 from the side.
(1) Run the cable along the trim piece.
(2) Work it just under the edge. It'll feel like there's not much room to fit it under there but there's just enough.
(3) Once the entire run is underneath you can grab it at both ends and gently work it up and over the wire bundle with a "flossing" motion.