From http://www.vodafone.co.nz/tv/vodafone-tv/ (Important things to know dropdown):
With Vodafone TV you can get a second Vodafone TV Digital Recorder for only $25* per month to receive the same channels you get on your first decoder.
*Standard domestic digital installs only. Additional installation and monthly charges may be applicable if you choose to have an additional decoder.
Therefore I imagine its just a case of asking for it when you sign up.
SkyGo works for me as an ex TelstraClear VodafoneTV customer so I'm guessing there should be no reason why not.