Asok:
The schematic files that are in the support ZIP for the app note you referenced are from a version of Orcad that dates back to DOS days (1995) that was called ORCAD-SDT/386. You will indeed have difficulty importing the xx.P0n files into the more modern Windows Orcad Capture. I tried to import them into both Orcad Capture 9 and Orcad Capture 7 and both gave errors of various types about the files including "premature end of file".

You may simply have to re-draw things from the PDF file.

On the other hand I would recommend ISP chips and use a Comm port. Use of old DOS derivative stuff on parallel ports will give you a multitude of problems getting it to work on the modern high speed computers in the days of W2k and XP.

Michael Karas