Wiring is present on all models. Just need the actual switch, and fog lights.
You'll need to add the lower fog light bracket, and then install the bumper cover. You also need to add the front fender GFX extensions forward of the front wheels.
Then the main issue is mismatch, as the GT body trim all around the car is different than that of an LX. So looking from the side, you'd see the different trims. Also, a GT bumper on an LX without the rest of the GFX looks like a beard.