If Roger or Mike! see this, I'm sure they will have some good advice for you.
You could put your footwear in a plastic bag, and put that in the foot of your sleeping bag.
Depending upon temps, just using them as a pillow(maybe with something soft on top) might do the trick. If it isn't too cold, maybe you could just stick them in your heated up sleeping bag in the morning, right after you get out, and the heat left in there might help.
But first, why are they getting wet in the first place? if from the inside, try using VBL socks. If from the outside, like snow sticking and melting, you might want to look into overboots (40below.com).
Also, the more breathable your footwear is, the more it will dry out overnight and the less it will freeze.