Modify the monsters skin's ?

[Vrrrr]

Hello, im working on a Bot whit autoit whit mouseclicks / pixelcolor's whitout any injection, and i wanna know if its possible to modify the .mpq files of textures or appearence of monsters

I wanna to add one green/purple square at the middle of the enemy to easy detect and kill whit pixelcolor

Is it possible?

Thanks!