Use a jewler's screwdriver or something similar to pop off the headlight knob, use some torx screwdrivers to remove the cluster bezel screws and then yank the bezel out and the switch is now accessable. Remove screws holding it in, unplug it, plug in new switch, and reverse everything. Literally a 5 minute job with screwdrivers.
2000 Mustang GT Steeda #0048 34k miles. 99 Cobra 4V swapped, FTBR IRS swapped, exhaust, tuned by James Gordon.
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.