[LE] How to change model of an in-game item?

[MuffinInACup]

Hi, I know this might be a very stupid question, but how do I change the model of an item, armor per say? I've extracted the needed .nif files from .bsa but when I try to edit model data in Creation Kit it says "invalid directory". Where does the nif file need to be to be in the right directory? I cant seem to open .bsa files with creation kit, only with BAE. An I cant write path myself, only to choose a file from the explorer.

[FrankFamily]

Skyrim directory/Data/meshes/some stuff/file.nif

[agerweb]

You have to create the directory like 'somestuff' in Windows and put your nif in it before you go into the ck. Then point an object (Static, Armor or whatever) to that nif.