Well, damn it. I had a feeling it will be harder than I thought. I'm using 3ds max 2016, since it's the latest version that has the nif plugin support. The thing is though, that I can't see the skeleton. The bones are listed on the left side, but they're not visible at all in the model (when x-ray is enabled or whatnot). Now I admit it's the first time I'm even using 3d program, but I've looked up why it may be so and only found out that it might be due to the plugin bug. Does it show skeleton for you normally?
It really seems that I went straight away for a deep water with model modding, just my luck.