edit:
READ THIS ENTIRE THREAD BEFORE PMing ME OR POSTING A QUESTION. IT IS EXTREMELY LIKELY THAT IT HAS ALREADY BEEN ANSWERED.
Ok, let's start this off by saying that you take responsibility for your own actions, not me or Pioneer or this forum shall be held accountable if you watch a movie and plow into and kill a family because of this functionality.
That said, a big thanks to a couple people on this forum, without whose help would have made this impossible (you guys know who you are).
-----METHOD 1 (can be tricky, but techies might want to know how it works)----------
After some extensive testing with the Z2 images and the CNDV700HD update disc, I've found the files responsible for allowing or disallowing the 2-wire bypass. To use these files, you will need to already have a Z2 (or Z1 with a Z2 image....hint hint), and have your hard drive unlocked. Simply download these files (link below) and overwrite them onto your SDATA partition (only overwrite the ones included). Like the Bluetooth update for the Z1, a zero-byte file called PRG.FLG in the root directory is the marker that the other files look for to allow the bypass. After you copy these files, a low-level reset is required (the recessed button next to the "face-down" eject button). Some of these files are already updated on the June version of the software, but to make this a one-stop-shop, they're included again for you anyway. Thus: This will work on any of the known Z2 versions.
Files:
http://www.megaupload.com/?d=9WRHDYJ2
-------------------METHOD 2 (assed out easy)------------------
CDROM ISO!!!!
1. Download this 30MB file: http://www.megaupload.com/?d=4T5MBJL7
2. Burn to CD or DVD as an image, not using built-in windows burning.
3. Insert in Z2, press Map, and run the update! (e-brake must be applied or wire grounded
4. Press the recessed reset button once, and your Z2 is now 2-wire bypassable.
This is for Z2 UNITS ONLY!!!! This will not upgrade your Z1, and actually might leave it unusable, as it relies on some firmware that isn't installed. Turns out the update disc was pretty easy to cut down to just the files needed to update for the bypass.
Enjoy!
Moderator Edit: if you want the directions to the 2 wire bypass it's posted here: