Allright, making some progress -- I tapped into the front left and rear left + speaker wires, and ran those to the amp. The front left wires were accessible (barely) behind the kick plate, and rear left wires were accessible in the bundle of wires running to the back of the car (not sure what it's called, but where you step to get in the front seat.
The 4 channel amp calls for connecting all 4 + speaker wires, and then there's a fifth wire to ground. No need to connect the high level - wires.
Anyhow, my biggest challenge was getting the 14 GA speaker wire into the door. I tried and tried to get it through the channel that was already there, but it absolutely would not go -- I think finally I realized why it wouldn't go, there are harnesses there, I don't think there's actually any space for more wires to go through there. So, I managed to pull out the boot from the door, poke wire through it (which was VERY hard because of the type of rubber, it's still watertight), and and then find another hole with a rubber plug to route it back into the car.
Power: Ready to Connect
Ground: Ready to Connect
Remote Wire: Ready to Connect
Left Front and Rear High Level Input: Ready to Connect
Left Front Speaker: Ready to Connect
Still need to connect the other three speakers, and the right inputs.
Below is a picture of the speaker wire running into the door.