Car on jackstands, disengage the hand brake in the cabin. Under the car on the inboard side of the rear hubs there is a little rubber grommet to remove that accesses the star wheel on the rear brakes. The parking brake is a drum brake in the middle of the rear rotor, turn the star wheel to loosen the cable just like how the adjustment worked on old vehicles with drum brakes.

The y-splitter has two pins that hold the left/right cable into the main cable. That metal bracket that joins it all together is part of the front cable and the two rear cables attach to it. Once the rear cables are loosened you just swing them outward a little till the cable lines up with that slot cut in the bracket then you slide that pin DOWN.

My parking brake is so loose I don't even need to loosen the star wheel, once I have both the rear cables unbolted from the chassis there's plenty of room to get those pins out, ymmv.

It's like how a lot of the cable/pin assemblies work for like door handle latches and stuff. Here's a pic of my car so you can see that middle bracket, I'll point to the cut out that you line up the cable on.

 

It's been a while but I ended up completing pretty much everything. I did run into the issue where I need my hazards but the wiring is completely different from the auto and the manual buttons, have you seen anyone else solve this before or know how to?