:!: CREDIT GOES TO Kendra_Sony as he sent this tut to me... :!:

Looks long but it works:

Requirements16GB USB configured for Xbox 360 Usage.Or if you have a Transfer cable, you can connect your Hard Drive directly.Horizon (Download)exiso (Download | Virus Scan)Acquiring the 'Content' folderNow that you know what you need, let's get down to getting the Content folder out of the ISO. There aren't really any screenshots for this part of the tutorial, as it's just a drag-drop operation at this stage. Probably the easiest part.1. Download 'exiso' from the Requirements section.2. Place 'exiso.exe' anywhere that you'd like.3. Note: Double-clicking on 'exiso.exe' will not do anything, it's mean to be used via command prompt operations or drag-drop operations.4. Navigate to where ever you have your Disc 1 ISO file. Now, select the Disc 1 ISO file, and drag-drop it into 'exiso.exe'5. Now, exiso will open and show some fancy command prompt stuff. Don't worry, it's just doing what it does, and copying the files out of the ISO into the same directory that your Disc 1 ISO is in. When it's completed, you'll have a folder with the same name that the ISO file has. Inside the folder, will be the Content folder that we need for the next step.Moving the files to the Configured USBThis step is probably going to confuse some of you, so I'll try my very best to explain it as clearly as I can. In the title it says 'Configured USB', this is reffering to a USB Flash Drive that was plugged into the 360 console, and set up to be used a Memory Unit. It is required for this, that the USB is larger than or has MORE than 8GB's of free space. (So using a 16GB USB Drive would be the way to go).Inside of your Content folder, you'll see the following files:Everything we need will be inside of the Content folder. Go ahead and open the Content folder, and also, open Horizon. Once Horizon is open, connect your Configured USB device.Inside of the Content folder, you will see a folder named "0000000000000000", which is the folder for things downloaded/installed to your Hard Drive. Onward, inside the folder open the "545408A7" and then the "00000002" folder. Now you're going to see the following files:Holy cow batman, what's all of this!? Simply put, these are the files that are holding all the pretty GTA files, maps, images, controls, etc. But, as you're here for install help, let's continue."Injecting" the files via HorizonWith your USB connected and horizon open, drag-drop the files ONE AT A TIME, into horizon. A window like this will appear:You're going to want to click the "Save to Device" button, then select your Device from the list. Do this for ALL FOUR files that were inside of "00000002". Now, I don't have any screenshots or videos for the following part (my HDPVR2 isn't hooked up atm, I'll try to take some ****** phone pictures later), but, let's continue. First, connect the USB back into the console. If you're going to play the game via the USB, this would be the end of the tutorial for you. If you're going to copy the files into your consoles Hard Drive, please continue. If you used a Transfer Cable to copy the files directly into your Hard Drive, then you're done.Copying to the Hard Drive from the USBNow, this is probably easy for most of you by now, copying from a USB to the Hard drive.Connect the USB.Navigate to System Settings > Storage > Memory Unit / USBNavigate to Games, and you should see the GTA 5 section.Press Y, click "MOVE", then select your HDD.When it's done copying, viola, you're done.Now, when you boot up Disc 2 for GTA 5, it should be working fine. Enjoy!

Thats exactly what he sent to me and it works
if you need help message him and he will help you!