You need to splice RCA male ends onto the harness, so front speakers have R+, R-, L+, L-, and rear has the same. You also have the center + and - which you probably won't be able to use. Just get a RCA audio cable and cut it in half. One half will be the front and the other will be the rear. They will be white and red with red being right channel. The wires will look like this (LINK).
If your new headunit has two sets of preamp outputs just plug the RCA's into there, no line level converters needed. If it only has one set, plug the fronts into that and use a line level converter for the rear. And if you have 0 RCA outputs you can use two LLC's but you would be better off getting a new headunit with 2 or more preouts.
As far as delivering power to the amps, if you cannot find the correct pin there is a way around that. You will need a multimeter, some tinfoil, tape, and a needle. Place the needle on the tip of the red lead on the meter, wrap it in tin foil and tape around it until it is secure. Set the meter to measure DC voltage. Ground the black lead and stick the needle into the back of each one of the possible wires (see my previous post) Have the headunit set on CD or TAPE, but NOT radio. Check for voltage at each wire, if there is no voltage this is not the right wire. If you find one with voltage (between 11.5-14.5), power off the headunit. If the voltage goes away that is the amp trigger, if the voltage is still there you need to keep searching.
It sounds more involved than it actually is. Let me know if you need clarification on anything.