With the system boots, simply stick a hair dryer in them on high for about 1.5 minutes, then put your feet in them and tighten them only the slightest bit to avoid "packing out" the liner material (this goes for just about all heat-moldable boots) Then let them cool to the shape of your foot for about 3 minutes or so, or until cool to the touch. Then you should be ready to shred with them!
Also, dont be afraid to give them a rip behind the boat as the insanely minimal heel/toe lift and incredible response make for one awesome ride! I never thought they would make a difference or be practical for the boat, but now they are all i want to ride!
Hope this helps. Shred on.