If its the ui_gadget file you have downloaded, then its really easy. Just replace downloaded ui_gadget file with that one in warband/textures folder. Remember to save the original file - in case you want it back.
It has to be the warband/textures folder NOT the textures folder in your modules/crpg. Though if you modifie your module.ini
you can make it too i guess.
Hope this helped.