You can name the head with the name that you want. Be sure that you put the PCreator Options->Texture file(s) checked. If you put Edit>TextureId to 0, that mean that Barret's head texture will be 'sbaC', 1 is 'sbaD', 2 'sbaE' ... 10 'sbaL'. Once you save the head, Pcreator will generate a .tex file of your texture (if you load it Ctrl+B and is is 256 colors). Then, check options>Battle model and go to File>Open Battle.HRC. Select Barret skeleton (sbaa) and set nº of textures to 10. Now, in kimera, you can replace the original Head with yours, and scale and move to fit with the rest of the model ^^
I hope that this was what you wanted