just get Z's mod, put vong models in XML folder, make a simple space map on the map editor, and thhe vong units should be somewhere. then, place them on the map, set affiliation to preferred faction and you can use them.
or if you're devoted enough, you could try to learn some coding and reskinning and make a personal mdod out of it. i mean, you've got the coral skippers, umfulluh, matalok, miid roiik and the koros stronha. no worldships, but mostly complete, some reskinning of infantry, and you could kind of piece one together. not as good as a model, and a little shoddy, but better than nothing.