I don't worry about it. I rest my edge across the top of my foot and the cable doesn't look any worse for the wear. The boot leather looks a bit scuffed up, but who cares? Just don't press down and saw your board back and forth against the boot (even then it probably wouldn't cut too readily). Have you ever tried to cut a cable with a straight metal edge? It probably takes a lot of work.
Just got some K2 T1 DB boots and they fit great. My board edge is quickly scuffing up the leather on my back foot, and I'm afraid it will cut through the BOA cable at some point..
Do you have conventional strap bindings? If so, before you get on the lift, push the highback all the way down, and lift the ankle strap straight up. Connect the strap and ratchet it a notch or two, to form a loop. Use this loop as a stirrup for your back foot on the lift -- much, much better than putting the edge of the board on your boot.
don't rest your board on your back foot and you won't have that problem?
Just loosen the bindings strapped to your lead foot a bit and let the board hang when on the lift. If you boots and bindings fit properly, you shouldn't experience much or any discomfort letting your board hang.
Or get Flows and just stick your foot in your back binding.
BTW, I cut the BOA cable on my Ride Jacksons my first season. Not completely through, but as soon as a couple of strands are gone, you just don't feel as confident. Fortunately, Ride sent me a new cable for free with no questions asked (except size and address )