It is not that difficult but there are some non-obvious issues to be
overcome. It is VERY important to install inline RF chokes on all of
the control wiring in and out of the Pactor, and in the power wiring
for your laptop. If your laptop is limited to a single COM port, and
most are, you will probably want a "serial port to USB multiplexer"
such as the one made made by Edgeport. That will allow your laptop to
receive GPS data at the same time it is controlling the Pactor/SSB.
Gary Jensen at Dockside Radio has a useful book:

http://www.docksideradio.com/