As a follow up for those interested in the future:
Steering wheel control wire is pin 18 on the ford 24 pin harness as seen in this diagram (note the connector is shown from the pin side, not the wire side):
Accessory power wire: I couldn't find the actual wire for retained acc, so instead I tapped into the fuse labeled 41 in the passenger kick panel. You will want to tap into the rear side of the fuse. This should show 0V when the fuse is removed and the key is in the "ON" position. You can solder a wire directly to the fuse, or you can use one of these:
Using this method instead of using an accessory wire from under the steering column keeps the radio on after removing the key, until a door is opened.
Reverse wire is green / brown and can be found under the passenger door sill in the large bundle of wires. There are 2 identical green / brown wires. I'm each goes to it's own backup lamp, but I'm not sure. I tested the first and it showed +12V when I put the car in reverse so that's the one I used.
Hope that helps someone else in the future.