Here's the schematic and the wire and assorted electrical work goodies that I purchased.  The schematic calls for the wire from the stereo to be connected to the far side of the dome light.  I thought this would be easy, simply run down the two wires from the dome light and figure out which one it is.

Here's the white wire coming from the back of the stereo unit (actually white/yellow stripe), I patched in the black wire I purchased at the store using the electrical crimp coupling.  Now all I needed to do was connect it to the proper car wire.

To get behind the dash I started taking it apart, yes I know, more car disassembly!  This kick plate is held on by 1 philips head screw and 1-10mm bolt. Note that the computer diagnostic plug is also clipped into this piece, but can be easily unclipped as shown here.

Underneath the plastic kick plate is a metal kick plate, this attaches with 2 - 10mm screws shown here. I removed this as well which opened up a LOT of space under the dash, I could put a SUB in here... :-)

For good measure I took the door sill off, it simply snaps into place with clips.  I examined the wiring harness here but could not find the color wire I was looking for. (At this point I was looking for a Red with Green Stripe as that wire at the dome lighted tested out as the one I needed to use.)

At last I found the wires I needed, they are inside the black wire tubing that ran alongside the steel structure tubing.  I spliced in the stereo wire and the installation was complete.  What caused so much trouble was that this wire was actually Red with a White stripe at this point, somewhere between the dome light and under the dash the wire changed colors! :-)

Here is another shot of where I patched into the existing wires.  Notice the steel tubing structure that is behind our dashes.  This is bolted to the side of the car, crawl underneath and have a look yourself!