Mal, I'm really not trying to be a pain, but would you do that on a conventional vehicle without (a) turning off the ignition switch or (b) pulling the 12V supply, much less (c) chocking/blocking the wheels? Killing power in the 12V circuit kills power to the relay that closes the circuit for the lines that run from the battery, within the battery housing.

The big wires are run under the floor, not through the door or roof, IIRC, and that is across the board. Again, check with a local dealer, but logically speaking, there is absolutely no reason to run wire further than you have to. The most cost effective path is under the floor. I've never heard of situation where you had cut through the underside of a car to extract someone. If it is that bad, you probably don't have a patient.

And if the crash is bad enough to cut the cables of the high voltage system, odds are the air bags have deployed. That kills the power to the relay for the main power. I belive the Toyotas are supposed to have a secondary accelerometer in the relay itself, to open it if there is more than a certain number of Gs.

I just raided my brother's bookmarks he left on my dad's computer. (The questionable joys of having to move back home.) Some of this might interest a number of us:
http://www.firehouse.com/extrication/archives/2001/july01.html (general)
http://www.extrication.com/ERG.htm (has links to manufacture's emergency guides)
http://techinfo.toyota.com/public/main/erg.html (toyota eremgency response guides only)
https://www.serviceexpress.honda.com/rjanisis/HYBRID.asp (honda's)
http://www.carsp.ca/hybrids.htm (from our strange sibling to the north)
http://www.hybridcars.com/hybrids-fires-emergencies.html (links at the bottom to everyone ERGs)

He had them organized in the same section as his stuff of HazMat. He carries the lookups on placards and what to do for various forms of odd HazMat in a binder that he keeps in his truck by his turn out bag. I think he's added the appropriate parts of the ERGs for the hybrids to that. As you said, first rule is protect your crew. And if that means you take two minutes, you take two minutes, same as at an unidentified hazmat.

That might not be a horrible idea- if the HazMat centers are willing, the could give a brief on the kills for the hybrids when the are called. Not sure if people would want a placard on thier car, but it's an idea.

Sorry, man, I'm not trying to belittle your concerns. I'm just saying that from what I've learned, the risks are mitigatable with training. If I'm right on the heavy lines being under the floor, then you should be able to do an extraction as normal.

I've given it thought, becuase as I've said, I know guys with them, I know too many (if that's possible) cops, firefighters and EMTs, and I'm big on alterntive fuels.

You want scary- a propane powered car with six 5 pound bottles in what was once the trunk. THAT is an FAE rolling down the road. And there is talk of using LP as an alt fuel in some circles.