1.Using ZLE2
Download here
a. Extract the folder
b. Run zle2_setup and follow intructions (must be Debug Rom)
c. Now run zobj_texture_export and enter the start and end offsets of the zobj. Start and end offsets can be found in the Docs folder called Object_list.
d. The texture will be in Textures folder and only touch the Bitmap images leave the RAW files alone.
e. Once you finish editing the images and save them run the Import Batch files in the textures folder and you will be done. :)
P.S
If you are running on a 64-bit computer you will not be able to do this.