i have no experience with orcad but i have used the libraries in the link you have given.
If your schematic is fairly simple , it may be easier just building up a netlist using a text editor and using a stand alone spice simulation program such as ngspice.
If this method is used all you have to do is
1) find the model that you need in the library file, copy and paste into new text file
2) change any instances of poly (from spice2) to spice3 format in your model.
3) write your netlist in this text file
4) simulate using ngspice
step 2) may be necessary if trying to use libraries in orcad