There's really no telling just how much truth a rumor packs until we can verify it for ourselves, but we've certainly been keeping our fingers crossed that Android 4.1 Jelly Bean's arriving on the Samsung Galaxy S3 is more fact than fiction. An update is said to be coming our way, possibly by the end of August, but we have no idea if it will really arrive by then.

If you can't wait to try this update, there are a number of ways to get your hands on Jelly Bean. Custom ROMs and leaks are definitely some of the best ways and the unofficial CyanogenMod 10 has nightlies that are available for flashing to the Verizon Samsung Galaxy S3.

XDA Developers member incubus26jc is giving Verizon Galaxy S3 users a preview of the delicious new software through a custom ROM. Because of the Verizon Galaxy S3′s locked bootloader, the requirements for this one are a little bit heavy and you'll need to refer to other guides to achieve root, unlock the bootloader, and install ClockworkMod Recovery. Make sure to be careful in reading the instructions. Don't get too hasty or else you might get into some trouble but we promise you that the experience of CyanogenMod 10 is definitely worth the effort.

In this guide, learn how to upgrade the Galaxy S3 I535 to Android 4.1.1 Jelly Bean via CyanogenMod 10 (unofficial).

Warning

• The instructions in this guide are intended for use with the Verizon Samsung Galaxy S3, model number SCH-I535. Applying these instructions on another device or model may produce undesired outcomes.
• The information in this guide is provided for instructional and educational purposes only. There is no guarantee that these instructions will work under your specific and unique circumstances.
• Use these instructions at your own risk. We shall not hold any responsibility or liability for whatever happens to you or your device arising from your use of the info in this guide.
• Read and understand the whole guide first before actually performing the instructions.

Requirements

• Verizon Samsung Galaxy S3 SCH-I535 with an unlocked bootloader, rooted, and with custom recovery (e.g., ClockworkMod Recovery or TWRP Recovery) installed
  • Check out the following guides to meet these requirements:
    • How to root the Verizon Galaxy S3 without Odin
    • How to install ClockworkMod Touch Recovery 6.0.1.0 on your Galaxy S3.
    • How to unlock the Verizon Galaxy S3′s bootloader. The procedure works on Linux and should work on Mac, as well. Windows users must exercise caution.
• A BitTorrent client (e.g. μTorrent)
• Download the following files:
  • invisiblek's CyanogenMod 10 Nightlies (d2vzw-CM10-invisiblek-KANG-08-19-2012-1438.zip.torrent, md5sum: 62b94fadb33c20a346b67b9982a2fd40)
    • Direct Link
    • Mirror Link
  • Google Apps package (gapps-jb-20120726-signed.zip, md5sum: f62cfe4a827202899919fd932d5246d7)
• On your phone, install the Android Terminal Emulator from the Google Play Store.
• Backup all personal data on your phone to make sure you have a copy of your personal data (e.g., contacts, SMS, MMS, Internet settings, Wi-Fi passwords, and the like) in case the procedure in this guide erases such data.
  • For backup tips, check our guides on how to sync your data to the cloud and how to create local backups of your mobile data.

Instructions

Backing up your EFS partition

1. Launch the Android Terminal Emulator app on your Galaxy S3.
2. Type in the following into the terminal emulator and press Enter:
   • su
3. Press Allow/Grant when prompted to give the terminal emulator root access.
4. Type in the following to backup your IMEI/EFS to your Galaxy S3′s internal SD card:
   • dd if=/dev/block/mmcblk0p11 of=/sdcard/efs.sbn
5. Your Galaxy S3′s internal SD card now contains the efs.bin file. Copy the efs.bin file to a safe location on your computer.

Installing CyanogenMod 10

1. Copy the CyanogenMod 10 ROM and Google Apps package to your Galaxy S3′s internal SD card.
2. Turn off your Galaxy S3.
3. Reboot into Recovery Mode. You can do this by pressing and holding down the Volume Up, Home, and Power buttons until recovery boots.
   • In Recovery Mode, use the Volume keys to navigate and the Power button to select.
4. Make a NANDroid Backup of your current ROM. You can do this through Backup and Restore and select Backup.
5. Select Wipe data/factory reset. Confirm the action on the next screen.
6. Select Wipe cache partition. Confirm the action on the next screen.
7. Select Advanced and select Wipe Dalvik cache. Confirm the action on the next screen.
8. Select Install ZIP from SD card.
9. Select Choose ZIP from SD card and select the CyanogenMod 10 ROM file.
10. Repeat steps 8 and 9 and for installing the Google Apps package file.
11. Select Go back.
12. Select Reboot system now.
13. Check your phone's IMEI number in Settings > About phone > Status.  If the IMEI field is blank or “0,” restore your EFS partition backup using the steps below.

Restoring your EFS backup

1. Launch the Android Terminal Emulator app on your Galaxy S3.
2. Type the following to grant it root access and press Enter:
   • su
3. Type the following to restore your IMEI/EFS Backup and press Enter after each command:
   • dd if=/sdcard/efs.sbn of=/dev/block/mmcblk0p11
   • reboot
4. After your Galaxy S3 reboots, your IMEI will be restored and you should be able to use the phone without problems.

Congratulations! You now have CyanogenMod 10 on your Verizon Galaxy S3. Do you find Jelly Bean's performance as buttery smooth as everyone says it is? Let us know by leaving a comment below.