Using a USB focus controller?

I'm wondering if I can control focus during a movie on a Nikon D3100 with a USB video controller? Or are there any hacks for the D3100 for movies?

Thank you.

Added (1). I know how to manual focus, I look for a device like that for using the camera on a crane.

Learn to do manual focus

Don't think so. This group didn't find an answer.

You may have to upgrade the camera.