Stright from Haynes Manual for 1994 thru 2003 mustangs.
"1998 and earlier"
--best i can do--
1. disconnect negative end of battery (possible airbag deployment)
2. take out the bulbs
3. detach the clip from the upper adjusting screw
4. squeeze the locking tabs on the lower two adjusting screws while pulling outward on the headlight assembly to detach it from the radiator housing.
I'd scan the page but my scanner isn't working (something in XP)
I would highly recommend getting a Haynes or Chilton's manual for your car. The headlights are a bit of a bugger to take off the first time, and the pictures in the Haynes guide help more than words do.
Those tabs are a pain in the ass to squeeze. There's 3 of them. One towards the middle of the car and two towards the side marker.
After I did mine I thought it would have been easier to use a socket (regular or deep) to make squeezing the clips a whole lot easier. There is enough play in the headlights that you can do one clip at a time. I used pliers and ruined the clips but I'm not using those headlights again. Check the light alignment before you put it all back together. I didn't and the passenger side points lower than the driver side.