Ok I've had several PMs about this and now I've finally got my digital camera working and got pictures uploaded and scaled and all that fun stuff. I apologize about the delay in time it took me here but hopefully this simplifies the process for anyone who wants to do it. If it's that popular I hope it gets the status of being stickied :)
Note: This process will INTEGRATE an AFTERMARKET head unit into the FACTORY AMPLIFIER. It will NOT bypass it, simply let the two pieces work together. This should also allow for factory tweeter function and if I recall correctly, factory sub as well.
Step 1: Obtain a harness (I used the Metra 70-1722) and a pair of 2 channel RCA cables you can part with.
Step 2: Cut the RCA's so that you have 4 individual male plugs with a small (6" or so) wire lead coming off.
Step 3: Connect the positive and negative wires of each plug to one channel of speakers off the aftermarket harness. One plug per speaker. 4 channels = 4 plugs.
Step 4: Solder and tape all your connections. You can use crimp caps and other connectors, but nothing will beat solder if properly done. You'll never see a crimp cap used in one of my installs.
Step 5: Tap the blue/white wire from your aftermarket head unit harness to the Light Blue* on your factory side harness. This will turn on the factory amplifier when the ignition is on. Alternatively and not as suggested, you could use the red wire. The difference is that the red wire will turn the amp on at any time you have the ignition of the car on, the blue/white will only turn the amp on when the radio is outputting an audio signal.
Step 6: Connect the rest of your radio harness wires to the harness you bought, red to red, yellow to yellow, etc. Solder and tape, etc.
Step 7: Plug in the harness, and connect the RCA's to your front and rear RCA pre-outs on your aftermarket radio! You should have full audio from your new head unit!
To assist, here are two pictures I have to serve as a visual aid:
*while it's normal that this wire is Lt. Blue, it's always smart to hook up the original stereo and test this wire to assure that it reads +12volts when the radio is on. This will assure that when you hook the blue/white wire to it that you won't zap anything accidentally. A good installer always tests before he connects.