There are some examples (at least one) of exporting OBJ files, maybe you'd have to go that route - like make your own .OBJ exporter with your amended UV coords, or even amend the UV's then save it as a .X for converting later.
Don't give up on AppGameKit
- there is always a way, to me it sounds like you might need some sort of model and texture setup program, which would let you add features as you need them, like setting UV coords dynamically, scaling them, splitting meshes, setting pivot points, all that stuff really.
I'm am 100% sure that V2 will have nice vertex manipulation like DBPro, I'd bet a kidney on it.
I am the one who knocks...