Remote triggering 5D2 via audio/USB

[sauvagii]

Hi everyone,

I'm sort of new to using ML (I used it a while back to shoot video on my 50), but haven't tried it on my 5D2 until now.

I'm trying to find a solution for me to remotely activate video mode on my 5D2 when I'm not around... here's the scenario.

There's a large-scale demolition happening across the street from me tomorrow, that I'd like to film.  Because I'm so close, I can't be in the house, so I had planned to hook my 5D2 up to a laptop, remote into my laptop and use either EOS utility or DSLR remote pro to trigger the record function a few minutes before the demolition happens.  (Tested this and it works).

The issue I'm finding now is that when the camera is plugged into the USB of the laptop, it's permanently on - so the battery drains.  I have to leave my property about 3-4hrs before the demolition occurs, so it's unlikely the battery will last that long.  I don't have a DC coupler for my 5D2, so trying to find a way round that issue. 

So - will the audio trigger in ML succefully 'wake' the camera from standby? (there's warning klaxons prior to the demolition), or can anyone suggest another way of 'waking' the camera via USB without having to physically unplug and replug the camera in?

Any suggestions appreciated!