5D MKII autofocus w/ cable release in live view?

Just got a 300/2.8 IS to shoot herps (and botanicals) for my 5D MkII. Did a few tests to assess best approach to reduce vibrations, and live view with cable release seems to be the optimal solution (as suggested by various other places). To engage AF in live view, one has to press the AF button on the body; AF does not engage when pressing down the shutter (on body, or cable release), which is mentioned also in the manual. The camera shake induced by touching the body with a 300 mm (or 440 with 1.4 converter) at close focus is staggering, beyond what IS can compensate. I do use a decent tripod (Gitzo 1300-series CF with Arca B1 ball head). Is there a way around it? Anything that starts up AF in live-view without touching the body?

Unless you want to do tethered shooting, with a laptop, then I don't think so. But why can you not AF with the AF-On button and then let go of the camera and release the shutter remotely, or simply AF with AF-On in Live View and then take the shot with the self timer? If you're in a rush then the 2 second timer should be pretty good. If you have time to spare then the 10 second timer ought to have you vibration free.

BTW, I have read that good old fashioned MLU is superior to Live View in terms of reducing vibration, although I don't recall the argument for why. Something to do with how the shutter curtains operate, I think. So if the only reason you are using Live View is to reduce shake, rather than to achieve mm perfect focus accuracy at a specific point, then you might be just as well off, if not better, by shooting through the viewfinder with MLU once you are lined up and focused.

Dear Tim,

thanks for the info. Tethered shooting is not really an option. I guess I have to live with the AF button. Re mirror lock-up, I did a few test shots, and with 2 sec timer and MLU, there is more camera shake than with live view. Easy to see by enlarging the frame 10x on the camera screen. I think that 2 sec is not enough to buffet out all the vibrations from the mirror slap. As someone pointed out, a one pixel shift in the image halves the resolution! At 6.7 micrometers pixel dimension and 300 mm focal length, the angular shift is minute.