One scrollbar to scroll them all

scrollbar_controller.js

// Hide scrollbars on the calendar day instances (jQuery fullCalendar plugin: http://arshaw.com/fullcalendar/)
var $scrollbox = $('.cal-item .fc-view-agendaDay.fc-agenda > div > div')
        // Hide the current scrollbars on a bunch of calendar divs (side-by-side)
        .css('overflow-y', 'hidden')
        // Since they're hidden and we're using another scrollbar to control
        // them, we need to bind mousewheel to make sure that we can still
        // mousewheel over the hidden boxes (jQuery mousewheel plugin)
        .mousewheel(function(event, delta, deltaX, deltaY){

            // #scrolly is my new scrollbar to control them
            var y = $('#scrolly').scrollTop();
            var strength = delta * 50;

            var dir = (delta > 0) ? 'up' : 'down';

            if(dir == 'up'){
                strength = -(delta * 30);
                y+=strength;
            }
            else {
                strength = (delta * 30);
                y-=strength;
            }

            $('#scrolly').scrollTop(y);
        });

$('#scrolly div').height($scrollbox[0].scrollHeight + 50);
// Now when I scroll on my newly created scrollbar, I force it to scroll the div's of the 
// calendar instances (that I set overflow-y: hidden above)
$('#scrolly').scroll(function(e){
    e.preventDefault();
    $scrollbox.scrollTop($(this).scrollTop());
});

// CSS
    #scrolly {
        float: left;
        height: 400px;
        overflow: scroll;
    }
    #scrolly div {
        /* height set via JS */
        width: 1px; /* firefox */
    }

// HTML
<div id="scrolly">
    <div></div>
</div>