Hey Rob,
You do not need to have a Static IP, you may also use a DNS service like the one offered for free by ChangeIP.com or any other service, and be set for streaming JP TV to NZ as long as the upload speeds where the Base is connected more than 300 Kbs and you on your end have High speed as well.
You may want to visit the following sites to read on Locationfree stuff:
http://www.changeip.com/locationfree/
http://products.sel.sony.com/locationfreetv/flash.html
http://products.sel.sony.com/locationfr ... index.html
If you have more questions feel free to email me. Info should be in my profile.
Stan