okay, ev fast override seems to work, only issues remaining are that the icon isnt updated (stays at +2 even if you set it to +10) and the value is reverted as soon as you go to playback mode and reenter rec mode. oh, and of course the keys arent mapped yet, i tested it in another way.
edit: overriding the keys seems to be the hardest part, or at least for someone who hasnt done hat before. i guess you are not satisfied with a shortcut like "half-press + left/right"
any tips by devs appreciated
in which modes do you need this bytheway, in all modes the normal ev override can be reached via func menu?