I wouldn't suggest cutting them any shorter, at least on the top laces. You need that top lace to be nice and long so that when you open the hinge you'll be able to open the binding more. If you cut the lace down you're not gonna be able to open it up as much.
On the back of the heel piece there is that pull handle to help you get into the binding. If you follow that handle down to where it connects to the binding, you should find a little elastic pull tab. Pull that little thing out and shove the lace through there...