It's up to you what kind of momentary action switch you'll add. It will need some kind of handy casing to fit your hand. Only single action switch is needed as the D70 does both focusing and triggering with the single pulse. I have used small Manfrotto 322RS switch box complementar to their 322RC2 ball head. It has two step momental switch, but I use only first stage (tip pole on 2.5 mm jack).