Working with someone else's code, so bear with me....

I've been asked to adjust the width of the below (currently 370px).

A Juice Control button is added next to a form element:

Code:
var btn = JUICE.UICtrlUtil.addButton(ctrl, "OrgUnitsearchbrowsebtn", "Browse", "Browse", "javascript:fireEventNoPopin(document.getElementById(\"OrgUnitfbtn\"), \"click\");");
The fireEventNoPopin function is:

Code:
function fireEventNoPopin(obj, evt)
{
    var fireOnThis = obj;
    if (document.createEvent)
    {
        var evObj = document.createEvent('MouseEvents');
        evObj.initEvent(evt, true, false);
        fireOnThis.dispatchEvent(evObj);
    }
    else if (document.createEventObject)
    {
        fireOnThis.fireEvent('on' + evt);
    }
};
When clicked, a new div is added at the base of the page:

Code:
<div id="popin_OrgUnit_p" class="selectFree" style="display: block; position: absolute; background-color: white; width: 370px; height: 250px; border: 1px solid black; overflow: auto; z-index: 1000; left: 493px; top: 833px; visibility: visible;">
I thought this may be defined by some Portlet or something, but I can't seem to find it. I'm trying to find the best way to increase this overlay's width.....