help me force liveview to work like a nikon's:

yeah, nikon, I went there.

When I had my D700 I could screw a 10-stop ND to it and liveview could see through it. It'd boost the ISO up high enough so it'd fake it for the rear LCD basically. With my 5Dii, when I switch to liveview during a sunrise shoot, it's normally black or damn close to it with just a CP and maybe a GND covering part of the frame... If I switch to M, 6400, and f/4 (17-40) I can then see through the filters. Any way to make liveview just do this for me w/o having to switch three settings?

I set my live view setting to exposure simulation. This allows me to put my 6 stop ND on and see the scene as it will be exposed.

To set it go to the live view menu and select stills or stills+movies. The next setting gives you the choice of stills setting or exposure sim.

thanks, I'll have to see if that helps enough with my 10-stop, but it certainly won't hurt!

In the exposure sim mode, the LCD shows what your exposure will look like, well as far as brightness goes. It should work with your 10 stop.