If you want to put aftermarket lamps in the stock fog lamp location, as long as they fit onto the bracket and are not more than 55 watts, you can use the factory wiring. I chose to mount mine elsewhere because 1) they're round, and 2) I wanted to have more control than the factory switch provides. As EMStaxi says, it's very easy to "replace" the factory fogs with aftermarket ones.
Actually, I think I'm about to take the factory fogs and bracket completely out and use that opening for ducted air either to the airbox, or back to the front brakes. When I bottomed out the front of my truck a couple of months ago, the brakets got bent out of shape, and they look bad right now. I'm rambling, it's 430, I'm going to bed.