Yes! If You don't feel like using joystick or mode selector You can use just paddles or sequential shifter. GCU would startup in Neutral by default, holding upshift signal for 0,5sec (user definable) will engage Drive mode 1st gear. From that moment shifting works normally. To switch to N hold downshift signal for defined time while stationary on 1st gear, and hold it again to enter Reverse mode.
Mode selectors are convenient to use, and recommended but in motorsport applications You can live without it :)