It can be done, but you already know that you'll still have the LX molding on the door. Finding the GT GFX and fog light stuff isnt too hard, but finding sideskirt brackets might be the hard part; sometimes theyre rusted off and theyre rivited on too. You can find them new, but the last time I checked a couple of years ago they were charging a lot for them. Also you'll probably be drilling a fair amount of holes in the body too.
For the wing, it would be easier to find a whole GT hatch with the wing, because the LX hatch has more bolt holes in it for the wing. Unless you want to weld/fill in the holes.
I'm not trying to stop you from doing it, just letting you know whats involved, maybe someone whos actually done the swap will chime in. I love the GT look over the LX, but if I had a LX hatch I'd put a Saleen kit on it because its easier and looks just as good IMO.
Yeah its a pretty lengthy swap, and a little pricy too, unless you've got a cheap doner car. I'd probably suggest just selling for a GT. It would be a lot easier