Ski boots are not ideal, but are actually do-able. I've taught a handful of crossover skiers in their ski boots. However those boards will be too unforgiving. They need more speed before they really want to carve. If you want a loaner board to teach friends on, look for an all-mountain carver like the Prior 4x4 (aka 4WD), Coiler All-Mountain, Donek Axxess (aka Axis), or an older Burton Coil, Wire, or E-deck. These boards have rounded tails that won't catch or want to hook up all the time, and they have deeper sidecuts that will be fun to carve at beginner speeds.