In reply to screeweasel:
Hi Andy,
Your problem will be with the boots themselves. Modern lightweight boots are designed for the mass market which means that they achieve their lightness at the expense of insulation. That's no longer a problem for the mass market because the alps in spring are no longer anything like as cold as they used to be. For high altitude, arctic or antarctic skiing these boots are just not warm enough. I've been on ski expeditions to Denali, Mt. Logan & Mustagh Ata with no problems using the legendary Scarpa Lazers, latterly with intuition liners (the old thick type), but you'll be lucky to find any in the shops. I took Scarpa Rush boots to Greenland and my feet froze so I scoured the internet for the last pair of Lazers in Europe I'd guess from the difficulty I had finding them.
One way of overcoming this problem is to get hold of a pair of boots a size or two larger and pack them with extra insulation even if it's only several pairs of socks and a foam footbed.
Overboots like the 40 below work better with Fritschi than pin bindings as you'll have to cut holes for the pins & the snow will get into them. Fritschi bindings just compress the neoprene as long as you've adjusted the height of the toe-piece. Yeti insulated gaiters which can engage with the dynafit pins with a bit of care are a better bet but often hard to get hold of in sizes that will fit ski boots - XL!
Good luck!
Dave