For the gutslut ending it's pretty simple, just be a gutslut (make all the vorny choices, basically)
1: after the chaser ghost sequence, say you are interested.
2: On the prison after getting the bishop key, when you are cornered by Mika, do as she wants and dont resist.
3: At the snake/stomach/woman puzzle, choose "the woman ate the snake"
4: At the abandoned mansion, after the convincing ghost sequence, you should be in a empty examination room with two chairs, interact with the one on the left, it plays a cutscene. After it, talk to the woman on the right chair.
5: When Nala asks you what you would do if she lost control, say you would let her eat you.
6: At the kitchen, offer yourself for the maid, but back down .
7: After feeding the said maid Paula, and she asks for seconds, choose "let it happen"
If it's done right, Nala should eat you at the piano room.
I think that's all what is needed, if it doesn't work, tell me.