Right, just posting the method Rizparky talked above (I'm a "he", btw XD). I'm using a rooted Android (Samsung Galaxy Mini) on 2.3.6 (with SuperSu):
1. Download RootBrowser
here
2. Browse your files, as in the pic below. Data >> .nvmac.info . Open it.
,
3. Edit the .nvmac.info file with the MAC you desire. Then save.
4. After you save, hold your finger over the file until some options appear (pic below), and select "Permissions".
5. After that, do this, keep only the "READ" options marked, then OK:
6. Change the SSID phone router to "attwifi".
7. Then, restart the phone router, and 1-2 minutes, it's done. This should work.
Sorry for my bad English.
