you needn't necissarily use o2 to change the texture path (i'm assuming the model is already textured... right?)
you can open the model in a hex editor and change the paths by replacing the respective strings. they must have the same lenght if the model is in mlod format. if it's in odol format then that doesn't matter really. (open the model in a hex editor and read the first lines. it will either read odol or mlod there.)
you can also use one of the texture swap tools. head over to ofp.info -> tools or search in the editors' depot here at ofpec, you'll certainly find some.
all you need to know is which texture is to be replaced by another one.