For skiers making the transition, go with what ya got. I started snowboarding on a yard-sale burton supermodel, TD bindings and my insanely stiff Lange Tii ski boots.
I think if you had a curious, motivated and tenacious skier who loves carving on skis, I'd suggest he/she start in their ski boots on a carving board . Just loosen the cuff buckle a bit. If they're already a soft-booter I think Slopestart's on the money, Most mortals though need hard boots of some sort to get the all-in carving feeling imho.