Well, I just looked at the forecasts for Sun Peaks and Kamloops, and it looks like they will be under the influence of the same major arctic air mass that the entire province of B.C. is shivering under, until Monday or so. If possible, I would try to postpone that trip. If you are unable to change your plans, prepare to battle the chill with everything you can comfortably move in. Plan to ski only during the warmest part of the day, early afternoon, and try to stay in the sun and out of the wind. I hesitate to ride on chairlifts in extreme cold, because if the lift stops for long while I am hanging in the wind with a wind chill factor of -40 it doesn't take long to freeze toes, fingers, and face.
You will notice your boots get much stiffer in the cold, so loosening the buckles a notch can save your shins and allow better circulation. I don't put on thicker socks, it just makes the fit too tight and reduces circulation. If you feel toes freezing, go inside and take off your boots right away. Helmet, goggles, and neck tube should fit to cover all parts of the face. One piece suits, so often mocked as fart bags on this forum, keep the heat in best, especially when topped with a down vest. Inside, expedition weight base layers and a thick wool sweater trap heat. If you drive up, don't forget to winterize your car. Make sure your antifreeze is okay, and hopefully you have a block heater, winter weight oil, good battery, and snow tires. And have fun.
Welcome to the Great White North, eh!