1994 mustang gt alarm

blue wire would be for your hood pin or trunk pin-the pin goes to ground when the hood or trunk is open so it's a negative trigger

green wire is for negative door pins but you have a ford so you won't use this wire

purple wire is for positive door trigger which you have.......tap the purple wire into the BLACK w/blue stripe in your Ford-find it in your kickpanel or at your door pinswitch.....it goes to +12 volts when your doors are opened so it would be a positive trigger

you are correct about your locks-if you have factory keyless then you have a negative trigger system

good luck

your car has a positive parking light wire....it is brown...you can pick it up right at the headlight switch or you can find it in the drivers' kickpanel area in the harness that runs toward the rear.....so take your RED / white wire and hook it up to a fused 12 volts (10-15 amp) and then take your parking light output wire what ever color it is and hook up to the brown wire I mentioned

To  save you some time, the doorlock wires in your car are

LOCK:pink w/ yellow stripe  UNLOCK:pink w/ light green stripe

Also found in the drivers kickpanel area where the wires run in from your door