Thanks for your responses.
I was doing a remote start at work today and tested the status output, and it does not transmit unless it sees ground on the neutral wire, so that method is in the toilet. Now, it looks like I'll have to use three (!) relays to make the ECU's neutral wire bypass the clutch. One to change the starter signal to ground to trigger the second one, which will basically change the neutral wire to ground-in-neutral, and use that one to trigger the third...
Wait, I just thought of a better way. Two relays. Nevermind. That's a little better.
As for the defroster, I'm not using channel 3 or 4, so that's not a big deal.
netZ, I think what you were thinking of with hooking the neutral wire to the hood pin was setting off the alarm if the car were left in gear. It wouldn't actually set it off, but it would bypass it for alarm purposes, which wouldn't be good. Plus it would ground out if the hood was open. I was thinking diode, but I don't think that would work either.
Mikkyo, what's an AND gate?
I do have the OEM alarm, which will of course be disconncted. I think I fried the LED output on it trying to figure out how to hook it up to the a/m alarm. Crap.