Well, disable it, restart your MacOS, do the changes and then don't forget to enable it again. Power the computer on (or restart it if its already running) and immediately. basically, you need to restart your mac in recovery mode, go to menu utilities and open terminal, type crsutil status to check if it is enabled or disabled, then you can use csrutil disable or csrutil enable. Plug your USB stick or drive in an USB port 2. Obs.: if your MacOS complain, you need to disable the CSR before change this. That's it, now when you open the Bootcamp assistant you can use the option that allows you to create a USB install boot disk. it will ask if you want to replace it, then you answer yes. Click Get or the iCloud download icon to download it. Select the USB drive as a startup disk when the option. Save this file, go back to the contents of the Boot Camp Assistant and drag the newly edited file into. Open this Mac App Store link.If your browser asks, select to open it in the Mac App Store. Press and hold the Option (Alt) key on the keyboard when the computer starts. In my case I changed from Macbook7,2 to MacBookPro8,2.

If it is like PreUSBBootSupportedModels, change the name to USBBootSupportedModels, expand this line and at the item0, edit and write down your MacBook model as a string value. Open this ist file with a plist file editor or xcode, then look for a line saying 'USBBootSupportedModels'. Then find the file ist and drag and drop to a whatever folder you created before. go to your application>utilities, select the Boot Camp Assistant app, right click > show packages content. This Mac OS 9.2. So, for those who can't create the USB install disk, here some tip.

Boot mac from usb stick