Yes, remove the nut that's on the outside surface of the bodywork. Turn radio on, and be prepared to catch the mast when it gets ejected out of the motor unit. Remove the motor unit from inside the car, open it up and remove any bits of the old toothed belt that might be around. Refit motor unit, turn on radio and push toothed belt on new mast into the hole (oo-er!).
When I did mine, I think I found that the Toyota manual gets it wrong when it tells you whether the teeth should be facing the front or the back of the car. Best thing to do is to study the motor mechanism when it's off the car. You should be bale to figure it out from that.
HTH