Pobably not the best for dexterity but try some sealskinz Gloves
http://www.google.co.uk/search?q=se...&spell=1&biw=1023&bih=434&fp=979f83dd7db9c2ef
they are really waterproof and not much thicker than a standard pair of liner gloves. No gauntlet so you shouldnt get as much water running into them. For extra warmth you could put a larger mitt over the top when you dont need as much dexterity.
I think whatever you go for the key is a modular approach and plenty of spares.
http://www.google.co.uk/search?q=se...&spell=1&biw=1023&bih=434&fp=979f83dd7db9c2ef
they are really waterproof and not much thicker than a standard pair of liner gloves. No gauntlet so you shouldnt get as much water running into them. For extra warmth you could put a larger mitt over the top when you dont need as much dexterity.
I think whatever you go for the key is a modular approach and plenty of spares.