Ok, after putting this on the backburner I was forced to figure it out today. Turns out I have been blaming Carbonite erroneously - many of my keybindings didn't seem to be working with ISBoxer because "Auto Self Cast" was selected in the GUI! Ugh - how much time wasted?

There must be an FAQ somewhere that recommends boxers turn that off; I know I'll be noting it for the future!