To unpack/repack VPP and STR2, you'll need the GIBBED TOOLS. You'll need the SR3 customization item's list to find the corresponding custmesh file. To unpack/repack textures you'll need the SR3 Texture Utilities. To update the ASM (required for item/texture mods) it's best in my opinion that you use an ASM_Updater.
You should end up with two custmesh files (one male and one female) and a customization_item.asm updated at the time you ran the updater all in the game's library (this is done lastly).
-The helm has it's own set of custmesh files as it is a separate item.
-The stag commando textures can be sourced from the characters.vpp_pc file.