Apparently some guy called "dattran" came up with this method but it is unknown who the guy is or where it was posted
FULL CREDIT to Ubergeek, here is his tut:
For this example we are going to use MW3.
1. Get a USB flash drive, At least 1GB in size and format it (FAT)
2. Insert into Xbox and goto memory devices. Select USB and configure it as a storage device.
3. Download this MW3 Title Update. http://www.multiupload.com/YNO57JNJNV
4. Download Horizon (Great game modding app btw - JTAG / Glitchers should be using the shit out of this - you can use other apps but this is my tool of choice). http://www.xboxmb.com/horizon/
5. Select Tools > Device Explorer
6. Plug in USB device to PC
7. Device will be detected. Select Inject File
8. Load the the MW3 TU that you downloaded.
9. Connect the USB stick to your Xbox. Restart and boot your MW3 backup.
Notes: You may have to delete the system cache after every time you do a fresh boot of the game. But hey, it works.
You can get other title updates from here: http://www.xbuc.net
Nothing is ever live safe. It may work, it may not. I'm not your mom make your own choice.
Please report if you have any success / links to TU's / better methods.