Have just discovered this great feature to make quick Itineraries for TomTom GPS - you go to http://www.tomtom.com/addto/route-index.php and I chose input by clicking on map, find Australia (or country you want) then just click away. It's much quicker than trying to put in an itinerary direct on the GPS.
The following button is a quick itinerary I did up from Warrnambool to Perth - I loaded it from here to the GPS.