Custom music theme svr 2011 using usb? (XBOX360)?

i wanna add custom theme to my svr 2011 but i don't have a cd. i know that you can't save a music in an xbox unless using an audio cd or stream those musics by mediacenter. what i wanna know is, can i plug the usb drive, not taking it off, and save it onto svr 2011 theme?