Not much to say on my end! About all I was brave enough to do was cut back all of the car stereo wires, because I knew they had neither power nor signal at that point.
I have heard that you can trace a given unused wire all the way back to the fuse or relay panel and ultimately pull the pin out there. You can also remove lots of unnecessary relays, depending on what accessories have been yanked out.
The ideal endgame includes moving the immobilizer box out from under the seat, along with the front fuse and relay panels, perhaps to the former passenger airbag dash location. Of course, that probably requires getting the whole harness out of the car first to unravel lots of wiring from the bundle. At a minimum, I'd recommend moving the immobilizer box as-is, off the floor, putting it in a plastic bag attached to the door bars of the cage, so it cannot get wet.
Here's a photo of my car during the interior tear-down, when it looked its worst!
tedious work by
bombaydigital, on Flickr