General :: Scrolling - Assign Commands Or Keystrokes To The Mouse Scroll Wheel?

I have a lil' problem with a new project. I'd like to find out how to set the ability to change to the next track in a playlist by using ongly the scroll wheel of a standard usb mouse. The objective is to assign a keystroke or a command to both mouse button 4 and mouse button 5 (scroll wheel up and scroll wheel down), so that a program like rythmbox or vlc would skip to the next or previus song in the playlist.