Actually, the code you need is in that wiki page. You just load some texture of yours and assign it to the manager with the name that it has in the file that you are loading. As mentioned in the wiki, this isn't the file name (or at least it doesn't have to be) but the name in the material definition of the file. For 3ds files, you can get these names from the loader if you have to. For obj, you can parse them yourself out of the mtl-file. Or just read them out of the log when you first load the file.