Some interesting ideas. If you read Cody Lundin's book, he spends a lot of time running around half naked in an attempt to acclimate his body to the cold. The problem with this that there's not a whole lot of plasticity in the physiology for this. However it has been reported by some and repeated by many that consuming lots of meat, especially raw meat, will prepare you well for the cold. This was talked about in a wonderful book on the Inuit, "Kabloona!" by Gontran De Poncins. Granted, the information is almost entirely anecdotal.
We also know that there is some genetic differences among mammals that use physiology to warm their bodies. This process is called Nonshivering Thermogenesis. Cody Lundin actually mentions this in his book but unfortunately he got the mechanism for this all boogered up. I asked him about this and he said he got it out of some book on outdoors medicine. I never did get around to checking that out. Anywho, mammals that are born and live in the cold tend to have a much greater ability for nonshivering thermogenesis than those from warmer climates. And these are genetic differences although NST can also be enhanced by acclimation (well documented in rodents). Very little though is known about this in humans. Brown fat is used as the main effector organ for this process and not much is known about the distribution of brown fat in adult humans (btw, this is a controversial issue), but large depots of it can be found in neonates around the neck, in the interscapular area, and a few other places. Finds of brown fat in adults have not been well documented.