Another note from the jeep side of life..lol
The rule of thumb that I learned was to size your winch for 1.5 - 2 times the weight of your rig. Another factor that comes into play when pulling is resistance. This would be in your case the deep snow. It is nearly impossible to put a number on this while in the field. Unless you are some tpe of super brain! Which I am not.
I use 9000lb warn units on my jeeps wich weigh in about 4000lbs
I do not know how many batteries the snowcats use, but I would try to have two batteries on them and a larger alternator. Even if you have a large enough winch you need to have the power to run it.
Make sure you place a weight on the cable. This will help it fall to the ground if it should snap. Be sure to keep your passengers away from the line as far as possible.
Or. You can convert to a sythetic line such as Amsteel Blue. It is lighter and falls to the ground if it should break. Does not kink on your winch like steel will do after several uses. You can also field repair it with out extra hardware.
Use a tree saver strap around a tree. Do not wrap the cable around the tree. It will damage the tree. I use one that is 3" wide and about 8' long.
Another nice thing to do is install in cab controls for your winch. There are some panel kit out there or you can get switches from Radio Shack and do it yourself.
Warn has lots of information on their site about winching techniques.
There are lots of good deals out there even on e-bay too. I bought a used 8274 Warn 8000lb unit a few years ago. It did not have a cable. Think paid about $400 for it. I have an Amsteel Blue line on it. The winch works great! It can carry 150 feet of line on it. It is really my favorite out of the three that I have. Hardly ever grunts when under load.
Another thing you can do to is get an extra cable with two loop ends on it. this is helpfull if your winch point is farther than your cable will reach.
We aslo use it to pull the jeep behind us when we do not have a straight pull path. We set up a snatch block straight ahead of the stuck jeep and the cable runs to the pulling jeep. Saves alot of time when your on a tight trail and it it tough to turn around.
Just make sure you pay attention to all the load ratings on each part of the system. It is like a chain. As strong as the weakes link. And on that note, do not use chains.... if at all possible. Bad thing happen!
Well I hope I did not blab to long. I guess I finally saw something I could reply to in this part of the board and share my thoughts.
I would buy a snowcat too.. but I have no place to run the thing. I would have to trailer it everywhere and I run my jeeps in the snow anyway!
Plus my wife would probably kill me..LOL or at leats kick me out..LOL
Have fun and be safe on those snowy slopes!