function scroll(e) {
                e = e || window.event;
                stopBubble(e);
                stopDefault(e);
                var window_top = $window.scrollTop();
                var delta = -e.wheelDelta / 120 || e.detail / 3;
                var move = delta * options.steps;
                slide(window_top + move);
                $document.scrollTop(window_top + move);
            }
jquery.scrolldiv.js 1.0
http://jquerywidget.com