How to implement server-side processing with jQuery DataTables plugin?

I am using the jQuery DataTables plugin to display a set of results combined from multiple tables. I am trying to implement server-side processing through the plugin to improve page load times. I can't quite figure out how to extrapolate the example DataTables gives to my scenario. Any ideas/suggestions?

Javascript:

$('#results').dataTable({
        "sAjaxSource": "../server_processing.php",  
        "bProcessing": true,
        "bServerSide": true,
        "bDeferRender": false, 
})

Original PHP Function:

function build_data_list(){

    global $org_id;
    global $dbh;
    global $req_ids;
    global $user_list;

    $sth = $dbh->query ("SELECT 
                        l4.name as L4name, 
                        l3.name as L3name, 
                        l2.name as L2name, 
                        l1.name as L1name,
                        u.id,
                        u.last_name,
                        u.first_name,
                        FROM user_grp_indx ugi, groups l4, groups l3, groups l2, groups l1, users p
                        WHERE
                        ugi.user_id = u.id
                        AND l4.id =  ugi.grp_id
                        AND l4.parent = l3.id
                        AND l3.parent = l2.id
                        AND l2.parent = l1.id
                        ORDER BY u.id", PDO::FETCH_ASSOC);

    $row = $sth->fetch();

    $item['user_id'] =  $row['id'];

    $item['user_info'] = '<a href="../users/index.php?pq=';
    $item['user_info'] .= $row['id'].'">';
    $item['user_info'] .= $row['last_name']. ", " . $row['first_name'] . "</a>";    

    $item['l1_name'] = $row['L1name'];
    $item['l2_name'] = $row['L2name'];
    $item['l3_name'] = $row['L3name'];
    $item['l4_name'] = $row['L4name'];

    for ($i=0; $i < sizeof($req_ids) ; $i++ ){
            $item['req'.$i] = (chk_req_status($item['user_id'],$req_ids[$i]) ? "<span title=\"Yes\"></span><img src=\"../../media/icons/tick.png\" alt=\"Yes\" />" :
                                                    "<span title=\"No\"></span><img src=\"../../media/icons/cross.png\" alt=\"No\" />");
    }

    $old_L1id = $row['L1id'];
    $old_user_id = $row['id'];

    while ($row = $sth->fetch()){

        $L1id =  $row['L1id'];
        $user_id =  $row['id'];

        if ($L1id == $old_L1id && $user_id == $old_user_id ){

            $item['l2_name'] .= "<br/>" . $row['L2name'];
            $item['l3_name'] .= "<br/>" . $row['L3name'];
            $item['l4_name'] .= "<br/>" . $row['L4name'];

            continue;

        }   

        $user_list[] = $item;     
        $old_L1id = $L1id; 
        $old_user_id = $user_id;

        $item['user_id'] =  $row['id'];

        $item['user_info'] = '<a href="../users/index.php?pq=';
        $item['user_info'] .= $row['id'].'">';
        $item['user_info'] .= $row['last_name']. ", " . $row['first_name'] . "</a>";  

        //add inital level stuff to the new record.
        $item['l1_name'] = $row['L1name'];
        $item['l2_name'] = $row['L2name'];
        $item['l3_name'] = $row['L3name'];
        $item['l4_name'] = $row['L4name'];  

        for ($i=0; $i < sizeof($req_ids) ; $i++ ){
            $item['req'.$i] = (chk_req_status($item['user_id'],$req_ids[$i]) ? "<span title=\"Yes\"></span><img src=\"../../media/icons/tick.png\" alt=\"Yes\" />" :
                                                    "<span title=\"No\"></span><img src=\"../../media/icons/cross.png\" alt=\"No\" />");
        }

    }

}

Original HTML/PHP:

<tbody>
    <?php foreach($user_list as $item){

        print "<tr>";
        print "<td class=\"hidden\">{$item['user_id']}</td>";
        print "<td>{$item['user_info']}</td>";
        print "<td>{$item['l1_name']}</td>";
        print "<td>{$item['l2_name']}</td>";
        print "<td>{$item['l3_name']}</td>";
        print "<td>{$item['l4_name']}</td>";

        for ($i=0; $i < sizeof($req_ids) ; $i++ ){
            print '<td>'.(  chk_req_status($item['user_id'],$req_ids[$i]) ? "<span title=\"Yes\"></span><img src=\"../../media/icons/tick.png\" alt=\"Yes\" />":
                "<span title=\"No\"></span><img src=\"../../media/icons/cross.png\" alt=\"No\" />").'</td>';
        }

        print "</tr>";  

    } ?>
</tbody>