Well, there is of course no fixed techniques in Toribash (Apart from Hold All/Relax All),
but you should just try with extending ankles and hips or something. Use whatever
joints you need to push yourself away from the ground. And if you need some
spin, try contracting one or both of your knees.
That, or try manipulating Uke into your foot (Without using his joints!).

Edit: It is very hard to get a decap kick at 100 engage distance, so you might
want to set it to like, 180-200...