VIDEO TUTORIAL
Download Links Below
[ame="https://www.youtube.com/watch?v=ETtlPpigUD4"]YouTube- How To Mod Your Gamertag With USB and EzGt 2.2[/ame]
More Detailed TUT when I get the time.

It has been confirmed that this can be done with a 1GB+ USB Stick.

Step 1

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Step 2
Open up USB HDD Explorer

Step 3

Click file in the top left corner, then select open device.
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Step 4

Click where is says content. Then select your profiles folder. This folder should start with a E0000 and proceed by clicking through all the folders until you reach the profile itself.
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Step 5
Next click on the file. Then click extract and save you your desktop.
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Step 6
Follow the tutorial here on how to edit the gamertag with EzGt 2.2
[ame="https://www.youtube.com/watch?v=iIK_kjAHisk"]YouTube- How to use EzGt 2.2[/ame]
Thanks to SuPaDooPaS for this TUT.

Step 7
Now once you have saved the modded profile it is time to inject it back into your HDD. So open back up USB HDD Explorer and click on content.

Step 8
Now take the gamertag folder you have saved to your desktop as it is shown in the ezgt 2.2 tutorial and drag and drop it into this section.

Step 9
Now just follow SuPaDooPas tutorial on how to use the account on Xbox Live.
[ame="https://www.youtube.com/watch?v=c5HE3S-OJe0"]YouTube- How to Activate Your Modded MW2 Gamer Tag[/ame]


Hope this tutorial helped! + Rep of it did!