I didn't add pins and I didn't mod the connector.
Did you take the boot off? There was a huge passage at the bottom of the connector on the sill side. I pulled Pear Cable Comice in there - as big around as your little finger, OD more like a 16GA extension cord. I put a little hand soap on it to help pull it through the Z-shapped rubber boot, but getting it through the connector was not a deal.
The driver's side wire passage in the kick is blocked by a module. I took out a bolt temporarily to get the wire through.
The passenger side passage was not blocked.
Both passages were plugged with gray foam plugs with a notch for the wire.
Would you like me to take pics of how to do it and post them?
Musicar Northwest Portland OR musicarnw.com
High-performance audio for BMWs