set multiselect lookup column using jquery

Question

I have a Multi select Look up column which as you all know is a control with two list boxes and "Add or Remove" Buttons.

The user populates the right-hand side of the control with some values by clicking the Add button; I have saved those selected values into array. Now the user changes an option in a cascading dropdown which actually populates this multi select lookup column.

Normally in this scenario, the default values are loaded into the left-hand side of the look up with the right-hand "Responsibility selected values" being blank. What I want to do is to load the right-hand listbox with the values stored in array.

I am open to a solution which is based on both jQuery and JavaScript Client Object Model. I haven't been successful so far. :( Please help.

 var newarry = new Array();
 $("[title='System']").change(function()
 {
  var responsibilityval = "";
  if(newarry.length > 0)
  {
 $.each(newarry,function(i){
 if(newarry[i] != '')
 {
 alert(newarry[i]);
 var mySelect = $("[title='Unit']");
 mySelect.prepend("<option value='0'>Before Apples</option>");    }
 });
 }
 });

I tried other options like but it dint work

var mySelect = $("[title='Unit']");
mySelect.val(1)

Javascript object model sample

 function getWebSiteData() 
{
    clientContext = new SP.ClientContext.get_current();
    if (this.clientContext != undefined && clientContext != null)
     {

            var webSite = clientContext.get_web();
            oList  = webSite.get_lists().getByTitle("Add New User");
            $.urlParam = function(name)
             {
                var results = new RegExp('[\\?&]' + name + '=([^&#]*)').exec(window.location.href);
                    return results[1] || 0;
                }
        var itemid = parseInt($.urlParam('ID'));  
        oListItem = oList.getItemById(itemid); 
        var listinfo = new SP.ListItemCreationInformation();
        var item =oList.addItem(listinfo);
        var fields = ['Responsibility'];
        $(fields).each(function(){
        var fieldName = this;
var field = $("#"+fieldName);
 var fieldValue = field.val();
        var entries = [];
    var newitem = new SP.FieldLookupValue();
    newitem.set_lookupId(1);

    entries.push(newitem);
        item.set_item(fieldName,entries);

        });
        item.update();
        oList.update();
        clientContext.executeQueryAsync(Function.createDelegate(this, this.success), Function.createDelegate(this, this.failed));                        
     }
}
function success(sender,args)
{



    alert('success');
}
 function failed(sender, args) {
 alert("failed. Message:" + args.get_message());
 }