Edit: You may be in luck, mduncan50. I found a DOS version pilot file editor called XWEDIT listed here
(it's actually a mission editor, but it also contains a pilot file editor). It may need an emulator to run on Windows XP, so I would also get something like DOSBox
. To convert the .plt file between the DOS and Windows formats, be sure to also visit the CRS Morning Star site (found in my signature) and hit the "Flight Deck" for Neill "Ranger" Magill's pilot file converter.
BTW, the Morning Star site also has mission hints in the "Tactical" section if you'd rather only edit the .plt file as a last resort.