http://www.stormcam.org/trunking-scanner-2/
how do i use trunking on my “radio shack pro97 scanner?
Programming a trunk system on the scanner can be a real pain to do. I recommend that you get a PC Interface Cable for your scanner and download a program called Win97. It has a much friendlier interface and will dump the programmed trunk system (and any other channels you wish to add) onto the scanner.
There are many places where you can find pre-programmed channels for different areas of the U.S. It may be that the trunk system you wish to listen to has already been programmed into a .p97 file that you can upload into your Pro97.
Radio Shack Pro 197 Digital Trunking Scanner – Phoenix, AZ PD frequencies