I just got my Nexus today (in Australia) and wanted to subscribe to Wired! magazine, as I have been a reader of this on the iPad since it came out.
I didn't fully use the procedure in the OP but I did add my Aussie credit card with a random US address in order to purchase the subscription (I use Tor to connect to US sites). Then I used Titanium to 'defrost' Google Play Magazines on the device and I have my subscription
Phone: LG / Google Nexus 4
ROM: Stock 4.2.2 JDQ39
Tablet: ASUS / Google Nexus 7
ROM: Modaco MCR 10.1 JDQ39