Hi mates,
I've just got my Nook Touch in Argentina (my father brought it to me from a B&N store in USA) and I could register it and buy books (from my PC) using a US shipping & billing address (I took one from a hotel by googling), my local argentinian credit card and using HotspotShield.
Just wanted to say that it is posible to have the Nook outside the US, you can buy books anywhere with a valid US address (from your computer, don't know if you can do it from the Nook itself), your own valid credit card and some VPN service that "fakes" your location.
If you can't do it, you must be doing something wrong. Please be patient and keep trying. Pay attention to every step and you'll be fine
If you try and try and still can't get it to work, fell free to PM me.
Regards from Argentina,
Lucas