If you have WP 8.1 dev preview you can try:
Source: http://www.wpcentral.com/bing-search-reveals-hidden-usb-settings-windows-phone-81
Now we see USB settings, but I don't know whether or not the feature works. Anyway - we see so that is already in the system.
- Launch Bing or Cortana
- Type in ‘USB’
- Swipe left to ‘phone’
- Tap Settings > USB
Source: http://www.wpcentral.com/bing-search-reveals-hidden-usb-settings-windows-phone-81