Changing Oakley lenses is easy it's a pop and a pull and then lining up the new ones and a few snaps and your in.Little bit of practice and you're golden. My .02 though it's a little bit more expensive to get a second pair of Oakleys vs just getting another lens. Pink iridium is usually pretty good for snowing and flat light. But in a white out there's nothing you can do.
Ice and a heating pad become your friend.