I trekked in cold weather with my cam before. Bring the following along:
1. A good cam bag (all weather bag recommended) to protect ur equipment.
2. A tripod as duffy mentioned.
3. A CPL as noob sniper mentioned.
4. More rechargeable batteries (if ur cam needs) for both flash or camera as under cold weather, batteries lose charge faster (Even my powerex lost charge within a day when i was travelling in weather of subzero to 5 degrees).
One more thing u might wan to take note is, when u arrive at the place, do not open up and take out your cam in the cold weather. A sudden temperature change from warm to cold is harmful for the electronics of the cam. Open ur cam bag and let air circulate for arnd 5 to 10 mins before taking out your cam.