[Samsung Galaxy Nexus] KShion619:
I know most people are on 4.4 by now, but I want to bring this tinkering I've done over the course of my Toro ownership over these 3 years to light!

So Here's Using the Final Google-Supported Build on Sprint's or Verizon's [Annoyingly] Left-Behind Variants and Getting by Verizon/Sprint's App "Compatibility Blocks" in the process!

What You'll Need

Official Google Takju/Yakju Images (I say Yakju since Google Wallet wont work anyways cuz Google Disabled it pre-4.4)

A custom ROM for the Version of Android you plan to use (ie: CM10.2 for 4.3.x or CM10.1 for 4.2.x or CM10 for 4.1.x or CM9 for 4.0.x)

ADB and Fastboot (Chances are if you're here you have these)

ClockworkMod for the variant you have (Sprint=toroplus, Verizon=toro, GSM=maguro Wait Why u reading this Maguro Users?)

A Galaxy Nexus (Any Variant)

Notepad++, Textwrangler, or any Text Editor of your choice

Zittoro's Tuna Converter Zip

7-Zip/WinRAR/File Roller/OS X Archiver

An Hour or less of your time

OPTIONAL: The Nexus Image for Your Variant for the Radios (If not already Updated)

RECOMMENDED: [MENTION=2562042]madd0g[/MENTION] 's BLE Libraries

Preparation of the Image

Unzip the tgz File Containing the Image Files as you would for a normal Image Install

If using WinRAR/7-Zip, open the ZIP file contained within and open with Notepad++ and edit these strings and save it back into the zip file

require board=tuna

If using Mac OS X or Linux's Built in Archivers, Unzip the ZIP File and Edit the text File and Edit These same strings and re-zip the folder so it looks (Almost) Unmodified, has the same files within as before

Edit the Flash-All.bat/sh and remove everything but these commands (Failure To Do So WILL Brick your Phone, double check multiple times, or... you know, copy and paste it from here! Assuming you are using the Yakju 4.3 Image)

fastboot oem unlock
fastboot reboot-bootloader
sleep 5
fastboot -w update image-yakju-jwr66y.zip

Triple Check you did everything (Dead Serious)

Now its time for the Fun Mod Part!

You know that allTuna-v4.3.zip i had you grab earlier? Open That in 7-Zip/WinRAR/Unzip it Under Mac or Linux

Remove Everything But the Variant Title You Have, Toro for Verizon, Toroplus for Sprint, and the META-INF File, we need that for Recovery to Read the new Zip

Edit The .sh File for your Variant and Remove the Lines that Involve

busybox sed -i 's/toro/maguro/' /system/build.prop

or whatever applies to your variant, AKA the first two commands in the file

Open your custom ROM and your alltuna zip side by side

Replace the files in the Alltuna.zip with the Custom ROM's versions, these will ensure they will work with your version of Android, the 4.3 version of alltuna is built with 4.3 and 4.4 in mind, but its always nice to grab newer, possibly more stable versions if they're avalible, right?

Re-Zip the Folder (If not opening Directly in WinRAR/7-Zip)

Final Stretch is Here!

Flash.bat/.sh, Run it but don't let your phone get to the welcome screen, in other words, when your phone reboots after the update flashes, pull the battery or something

Run this command to temporarily boot ClockworkMod

fastboot boot recovery-clockwork-6.0.4.3-toro.img

(toroplus in the case of Sprint, you should know this)

Flash AllTuna.zip that you modified!

adb sideload alltuna-4.3.zip

Reboot Back to the Bootloader and Lock your Phone! (Makes that ugly Lock not show up)

fastboot oem lock

Boot Up your phone into your new Stable GSM Modified ROM!

Optional Tidbits

Rooting Flash SuperSU 2.-- From Here

Credits

[MENTION=5144644]Zittoro[/MENTION] for Base Conversion Kit

[MENTION=631273]Chainfire[/MENTION] for Root

Google for Nexus Images