Modding character models

Hi everyone!
I have a (maybe) stupid question and ask for help. I want slightly modify this Graphic Boost client with some "spicy" models of players character. - It just change the appearence for you, nothing else. I tried it on another private server where WoD version of the game was playing.
It was really sipmle modding- you just put in directory of game a folder called "Character" with the data of the mod.
I just want to know if i need models for WoD version or WotLK version since the client is 3.3.5. but models are from WoD.

Does anybody here have any experience with this or am I completely lost?

Thank you very much in advance!

So I kinda move forward but still not solve this.

The thing is I have MPQ files with skins which are working on classic WotLK 3.3.5. client but when I put them in Data folder in Graphic Boost client it doesnt work. (Game crashes)
It will be probably because MPQ files in boosted client are changing models to Legion one.
So I downloaded skins for Legion, then make an MPQ patch from them, put them to Data folder but it doesnt work either.

Is it because I have wrong version of skins or Iam I doing some mistakes in MPQ converting? Iam using MPQ Editor v 4.0.0.905.

The structure of my MPQ fle is:

Patch-X.mpq
- Character
- Nightelf
- Female
- (here are skin files)

Can someone help?
Thanks!