read this, or read me 🙂
the AngelXwind repo realeased a tweak renamed to (Google Voice SMS) (which is SMS GV Extension compatible with iOS 6)
You just need to download it and do the same steps you do for the SMS GV Extension (like to activate) this works for me on my iPod 4 🙂
The only bug I have is when I use BiteSMS and replying to a text message, it wont let me send unless I got to my native messages app and send it.