Q:

Sort taxonomy page alphabetically by meta rather than default post date

The user starts at a page showing posts of custom post type, "agent".
Each post displayed shows a region/custom taxonomy it belongs to and links to a page that shows all posts in the region the user clicked.
This is how these posts are currently displayed,
<?php while ( have_posts() ) : the_post(); ?>

Ideally I'd like to to sort these alphabetically by meta_key lname rather than by post date which appears to be the wordpress default.
Thanks for any input
Edit: Script I use to get all custom post type Agents. Puts one specified post as last post. 
<?php 
    $loop = new WP_Query( array( 
        'post_type' => 'agents',
        'orderby' => 'meta_value',
        'meta_key' => 'lname',
        'order'=>'ASC',
        'meta_query' => array(array( 'key' => 'lname' )),
        'post__not_in' => array( '93' ),
        'posts_per_page' => -1 ) );
    $loop2 = new WP_Query( array( 
        'post_type' => 'agents',
        'post__in' => array( '93' ) ) );
?>
<?php
    if($loop->have_posts() || $loop2->have_posts()) { 
    if($loop->have_posts()) { while($loop->have_posts()) { $loop->the_post();
?>

A:

This is what ended up working.
global $wp_query;   

query_posts(array_merge(array('orderby' => 'meta_value', 'meta_key' => 'rw_lname' ),$wp_query->query));

<?php while ( have_posts() ) : the_post(); ?>

