Dont quote me on this but take a look. The wiring should aready be there. All you need is a switch that should be placed in your middle console (probably a coin holder there now remove it), fog lights, fuse underneath the hood. In my 94 thats all I needed. Best bet is to take a look at a chilton's manual.
http://mustangworld.com/ourpics/fcar/ctips.htm There are two spots on there about fog light installs. Hope they help.