If you need 512 textures only for texturing purposes, the easiest way if you don't have 512 textures is,
to copy a custom folder of someone who uses full textures (no matter if 512 or not) or changing the item.dat file, so the tori uses textures.
Then just give the folder a good name, e.g mine are called 0pt(Number Here).
Then start texturing and when saving,
also save it into your new custom folder and overwrite the needed body part.
(Even if the player only haves 128 textures, it will be shown as 512 textures as long as you made it as 512 textures.).
Then just lp it ingame, if you like it fine, if not just edit a bit, overwrite the old file and lp again; thats way easier than uploading it all the time
I hope its understandable D:
How about 40k? 
