Then using the Benm alternative is best.
1. Go to Cydia
2. Install repository iFoneguide.nl
3. Install tethering patch (3G or 3GS depends which one you own)
4. Go to
http://help.benm.at
5. Look for MobileConfiguration
6. Install the carrier bundle that best suits you (here in the US either T-Mobile or AT&T)
7. Go to Settings => General => Reset => Reset Network Settings
8. iPhone reboots
9. Go to Settings => General => Network => Internet Tethering... turn off/on on Bleutooth or USB.
10. ????
11. PROFIT!