Some older Mac users want to install Windows, but find that boot Camp Assistant (BCA) on their system does not have the option of installing Windows on USB.
Below take my MacBook Pro (13-inch, late), OS X EI Capitan as an example, let BCA support USB installation Windows.
0. Open "/applications/utilities/system Information.app" and note the value of "Model Identifier" and "Boot ROM Version" (My machine is "macbookpro8,1 "and" MBP81.0047.B2C "), which need to be used later.
1, first copy "Boot Camp Assistant.app" from "/applications/utilities/" directory to "~/downloads/" directory.
2. Open the "~/downloads/boot Camp assistant.app/content/info.plist" file.
3. Find the "Preusbbootsupportedmodels" key and change it to "Usbsupportedmodels".
4, in the "Usbsupportedmodels" key, the No. 0 step down the "Model Identifier" appended into the array. As follows:
<Key>Usbsupportedmodels</Key><Array> <string>MacBookPro8,1</string> <string>macbook7,1</string> <string>macbookair3,2</string> <string>macbookpro8,3</string> <string>macpro5,1</string> <string>macmini4,1</string> <string>imac12,2</string></Array>
5. In the "Darequiredromversions" key, append the "Boot ROM Version" noted in the No. 0 step into the array.
<Key>Darequiredromversions</Key><Array> <string>MBP81.0047.B2C</string> <string>Im41.0055.b08</string> <string>Im42.0071.b03</string> <string>Im51.0090.b03</string> <string>Im52.0090.b03</string> <string>Im61.0093.b01</string> <string>Mp11.005c.b04</string> <string>Mb11.0061.b03</string> <string>Mbp11.0055.b08</string> <string>Mbp12.0061.b03</string> <string>Mm11.0055.b08</string></Array>
6. Save "info.plist" file.
7, signature. Enter the following command in Terminal:
sudo codesign-fs-~/downloads/boot Camp assistant.app/
8, run ~/downloads/boot Camp Assistant.app, you can see the BCA more "Create a Windows 7 or later version install disk" option.
Reference:
1. Bootcamp-no ISO Option (http://apple.stackexchange.com/questions/170759/bootcamp-no-iso-option)
How to make an old Mac machine support USB installation Windows