Razer Viper Mercury: Middle Wheel Click Scroll Mode Setting?

Hi there, I purchased a razer viper mercury (the version with the cord) and there is one setting I can't seem to find: How do I set the middle mouse wheel click to start the scroll mode? On my former mouse it used to be that I could click and hold the mouse wheel and then move the mouse up (for scrolling up) or down for scrolling down. I am aware I can turn the wheel to scroll, but its just not as comfortable :-) I think I am missing a setting, hence the question. Thanks