This is a 2 part issue.
A) I cannot bind Mouse Button 5 + W for stance adjust up (and A, S, D for left, down and right). When attempting this, the result is the keys Mouse But. 5 AND W being added. Not Mouse Button 5+W.
Example: http://i.imgur.com/fu30lj4.jpg?1
B) keyAdjust[]= does not function in the Marksman update.
In a workaround attempt to add a value here from my old(1.38) config, keyAdjust[]={65540};, I was not able to stance adjust using Mouse Btn. 5 + WASD. I then found changing this value to 29, for left control, I still could not stance adjust.
It appears the only way to stance adjust is to use the new Stance Adjust binds in the game, or the keyAdjustUp[]=; keyAdjustDown[]= ect. entries in the arma3profile config.