I followed James' instructions. I went directly to the AT&T store and had the data blocked from my daughter's Samsung phone. They even gave me a confirmation receipt. Next, I connected the iphone 3G to Wifi, without any SIM card. Then I went to unlockit and installed a fake APN (it even saved an icon on my phone like an app). Then I inserted the card into the iphone.
His system worked - for about two weeks. My daughter just received a text from AT&T stating that a data plan is required.
Although James was adamant that his method works, I can assure you that it does not.