I didn't use a single 5-pin relay in my wiring (I mostly left the Sierra relay box intact) and just one normally closed relay for the ECU's fan control.
Have you found David Murray's excellent wiring diagram? It was all the inspiration I needed to wire my car. All the fuses, wires and relays are listed with their ratings, as well as the pin numbers for the Sierra column switches:
http://www.haynes.co.uk/forums/showthread.php?t=4763