Best shipping module to use in this situation?

I have multiple regions made up of multiple postcodes in Australia, each region has it's own flat shipping rate and then an additional per kg shipping rate on top of this. It sounds simple but I cannot figure out the best way to implement this?

Is there a module already available or a module that would be easy to modify? I have very basic PHP knowledge... The Zone Shipping module looks kind of like what I want except that it uses countries instead of postcodes, is there a way to change that?

Any help would be great, thanks!

i haven't gotten that far yet with my own zc implementation but i'm pretty sure i've seen posts from other aussie e-tailers using zencart, where not only do they do what you are asking for here but more.
if you don't get a response, keep trying as i'm sure someone will come good for you!

andy