If you bought em during the summer I'm guessing you haven't worn them right? Maybe see if your store will let you exchange them for something longer before you go hacking away on them.
Otherwise you could go the complete other way and rip 'em off at the hip daisy duke style and get some flesh colored leggings to go under them for warmth.
Summer sale = no returns. Asked Burton but didn't get a reply. I might post a pic of how it looks now but i like my pants a little longer, but by no means baggy.