I am the friend MK mentioned speaking with.
As she said there really is no one way to do it. If there was, there likely would be a much more user-friendly way of installing models like that by now.
What I have (the stuff I showed off in my Character, Roleplaying, & Screen-Archery Thread) I got to after learning very much, and a lot of trial and error.
I plan on making a post in the future elucidating some of my discoveries (much, much easier animation editing, a more detailed guide on extracting and converting sliders, maybe some resources I’ve made myself, etc, etc).
I just have a lot on my plate (bah dum tiss) right now (real life, secret project, public project, writing, modding different games in my spare time, etc, etc), and I do not feel like doing tech support for it. Also, my methods do not allow for some coveted things people besides me would likely want. The main example of that being Real-Time Weight Gain (I like making a static model as opposed to the dynamic slider method some have preferred using due Skyrim’s animation limitations and the models even with special sliders generally needing a lot of manual tweaking for it to look good).
For now, before I’ve made my post, I would recommend what others have said. Devourment sliders for feminine characters (you can choose to just extract the sliders if that’s all you need/want, and are a more experienced user that’s willing to get down-and-dirry with Bodyslide & Outfit Studio), and Shape Atlas For Men sliders for masculine characters.
As MK said, if you get some results you like, post pics either here or on my Screen-Archery thread. I’d love to see them! Sorry I can’t be of more help currently.