I was able to fix this pre-cyan update using teh foreign sim card trick. BUT now that cyan has come out it no longer works. AT&T has changed something in the latest build and i am back to having teh upsell prompt when ever i try to turn on internet sharing.
Please ATT tell me how to fix this.
btw I got it to work on anotehr 1020 from rogers wireless so i know the problem is related to teh ATT build.