Thanks KCY. Got it. It was so simple, feels like DOH!
if you just press the Q button it brings up the quick change menu. Somewhere on the right there's an icon that's a shortcut to re-assign all the buttons that have the option. I can NEVER remember where it's buried in the menus so I use the Q shortcut personally. 
But....using the DOF button for switching to AI servo...only works while the button is pushed in. You have to hold it in to keep the AI servo, so it's only half helpfull!
I would have disagreed last week, but I shot my first wedding with my 5D3 this weekend and switch back and forth a lot. Combine the DOF as focus type switch with rear buttons to focus and it's a hand workout for sure.















