You would need to be a very experienced hiker in order to do the Torres del Paine hikes in the winter. The refugios are closed, so you’d have to carry all your winter camping supplies on your back and also be sure of your ability not to wander off a snow-covered trail. I remember reading somewhere that you may actually have to convince the park administration that you have the skill to hike in the winter and not die because they don’t want to have to go looking for hikers.

I imagine that you would also have significant difficulties travelling overland during this time of year. I went in spring and had some weather-induced bus delays, which you can read about here toward the bottom of the page: http://www.livejournal.com/users/cestovatela/32825.html

Definitely write to some travel agencies in the area to see if the kind of activities you’d be interested in will still be available. The things I did, like horseback riding and day cruises, would probably be impossible because of all the snow and ice.

I understand your adventuring spirit and I wouldn’t want to discourage you from something that might actually be possible, but it would definitely be a good idea to know what you’re in for and know what you’ll be able to do at that time of year.