In my head, there are two ways taming the various usually violent beasties could work.
1. Just like the other animals through a long breeding process. You capture a male and female wolf, bear, moose, etc. and eventually a more docile generation will be made that you can put a collar on and it is now a pet.
2. Wild Animal Reputation. Being able to leave pikes of meat, hunted animal carcasses, baskets of berries, or other desirable food items in areas that spawn wolves, bears, moose, and elk could make them less likely to attack you in that area because you are feeding them. And then once they like you enough, you can hand feed them and that's when you've tamed them.
Then, when they are tamed, they can do a few things for you. Bears and wolves can help hunt as well as help herd animals into pens. Moose and bears could be ridden like the elks can already, with the moose being able to hold more supplies than an elk. And they all could be put on a guard mode, targeting monsters and warding off any of their wild counterparts.
I don't have the know how to make any of this possible in a mod, and I don't know if there is a mod that does something similar, but I just think it would be a cool thing to implement into the base game. Let me know what you think!