There's no Program. Search for the nVidia DDS Plug-in and open the clothes with Photoshop. Change it as you like and save it with a new name (but with same character's size). Then, find the .elu file that corresponds to the model-base and copy and paste it, and rename it to a new name. Open it with hex editor and edit the name to the name you gave to image you edited and change the meshname (search for eq_chest for example and change the number to another one). Open woman01.xml or man01.xml and put a new tag referring to the new .elu file you made. Then, go to zitem and build up a new tag with the new meshname. Put the ID in the shop and you're done.