G'day alco_power,
If you wish to cover the entire distance between Murwillumbah and Newcastle, then doing it in sections is the best way to do so. I have successfully recreated the distance between Brisbane and Toowoomba, this way. It has to be kept in mind that limitations still apply (the Toowoomba route came in six parts) and that TransDEM has a limit of 32 MBytes for any files that must be georeferenced, over and above this.
As geophil (the creator of TransDEM suggests, read through the freely available TransDEM manual (and look at the tutorial on how to create a route for an English layout) and it should all come together. Between the two of us (geophil and myself), we should be able to steer you in the right direction..
Jerker {

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