You might wonder what someone from a completely different part of the world is doing here...
Well, I happened to create DVBE4SAGE plugin that allows people to use SageTV with their encrypted SAT providers using standard computer DVB-S(2) cards their legal subscription cards. And, it happens to work quite well with Sky NZ!
You can find more info on it in this thread on Sage forums.
If you want to give it a try, please, PM me, and I'll provide you with the latest version as well as installation instructions (BTW, those were written by your fellow NZ guy).