From ModMyiFone - Wiki
This tutorial won't unlock your iPhone 3G!
To follow this tutorial, you must have the following:
Here are all the steps you need to follow:
1. Download all the files mentioned above.
2. Install Winpwn 2.5
3. Create a new folder named WinPwn (or whatever you like) and place the winpwn shortcut, firmware file and BL files in the folder.
4. Open Winpwn and select the first picture representing iPhone 2G.
5. In next step, select 2.0.2 and click next.
6. Then, it will ask if you want to use the official carrier. Click thumbs up for yes and thumbs down for no. Skip the next step if you click thumbs up in this step.
7. Now, it will ask if you want to unlock. Just click thumbs down if you only want to activate and click thumbs up if you want to unlock.
8. Then, it will ask if you want to use custom boot logos. Click thumbs up if you want custom boot and recovery screen logos but if you choose thumbs down, skip the next step.
9. Now, click on the two iPhone pictures to select the different boot and recovery logos. If you want to search online gallery, first click on browse so it changes to online and then click on the two iPhone pictures.
10. When you click next, it will start building the custom firmware.
11. After custom firmware is built (will be saved in My Documents), you will be asked if you want to start the DFU wizard. Click thumbs up.
12. Then, it will ask if your phone is turned off and connected via USB. If not, then do it and click thumbs up.
13. After that, it will give a ready to pwn message. Click OK.
14. First of all, press and hold power button till countdown ends.
15. Then, hold both power and home button till countdown ends.
16. Then, release power button and keep holding home button till countdown ends.
17. After you get the success message, release home button and quit pwnage.
18. Then, open iTunes to restore to the custom iPhone firmware in iTunes. To do this, while holding shift, click restore and select the custom firmware.
19. After the phone reboots, it has been pwned successfully with Cydia and Installer on home screen
Notice: If you face crash while building firmware, use the expert mode and set partition size between 700 MB to 900 MB
All credits go to CMW and DevTeam for this software.
