install speed sensor on 91 accord?

I'm having a problem with my supersport indicator light flashing in conjunction with my speedometer not working. I'm told I need a new speed sensor installed. My Chilton manual doesn't give good instructions on installing a speed sensor. Is this difficult to do or should I take it to a mechanic?

Here you go.
http://www.hondapitstop.com/accord/technotes1/engine/speed_pulser/speed_pulser2/speed_pulser2.html