This is similar to the project I did.
I don't know of any other members with fully worked systems. I went with new HU too...
Pioneer Avic N4 flipout DVD / Navigation unit
Phoenix Gold XS6600 amp (600w x 6 channels)
Rainbow 365.25 3-way components up front (6.5 woofer, 4 mid, 1.2 tweet)
Tang Band 6.5" maxX woofers
Stage: Bridge 2 channels for each side of the front 3-ways (200w per side), 1 channel for each TB woofer, set at 100w each.
My question to you would be why aren't you going to run a new HU? If you use the stock, you'll have to LOC the signals since you can't get a tappable HU out, and you'll lose quality through the amp's processing. You'll also have to loc ALL of the speakers together back to that cleansweep to let it process and create a full range signal. Obviously you've thought of this already, but I'm curious why you would go through all that hassle, extra equipment and wiring, when replacing the HU would go miles for improving the path, not to mention allow better aftermarket integration.
Just a thought.
I have a huge writeup over on bf.C site of all of this if it can help, and I'm around all the boards. Also, be ready with your dremel for mounting the tweets, they were a pain!