ML is filled with clever possibilities. I set up ML My Menu the first day I had my 5d3's, and of course the wb adjust got a prominent place. But whenever I select ML, the menus pop up somewhere else than in My Menu, so I have to navigate a bit with the joystick. Not a very big problem, but...
I have set up My Menu in the Canon menu system as well, and the Canon-version can be set as default so it pops up every time. Would it be possible to read the associated flag or register, and - if set - the ML version of My Menu would also take priority and pop up right away all the time as first menu choice? That way the ML My Menu could reuse a Canon Menu feature and avoid having to get a register or flag of its own.
Then wb adjust would be right under your thumb every time.