My original (v1) version of the voladj on/off used button chords, so, yes, they're possible.

Double-clicks have also been on my mind, but they don't work well on the knob (too easy to spin it while pressing, and things WILL get confused). But they work just fine on the other four buttons (and those are available on mk1 as well).

But maybe simplier would be to redefine the press'n'hold FF/REW functions (front panel), since they are rarely used in the car (and if needed, the menu is there to reenable them..).