Sure, the members.php is only some changed HTML (and something extra to the query, to retrieve the CS nick, which replaces Jabber) 
EDIT:
Here's the code
<?php
/***********************************************************************
Copyright (C) 2002-2005 Rickard Andersson (rickard@punbb.org)
This file is part of PunBB.
PunBB is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published
by the Free Software Foundation; either version 2 of the License,
or (at your option) any later version.
PunBB is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston,
MA 02111-1307 USA
************************************************************************/
define('PUN_ROOT', './');
require PUN_ROOT.'include/common.php';
if ($pun_user['g_read_board'] == '0')
message($lang_common['No view']);
// Load the userlist.php language file
require PUN_ROOT.'lang/'.$pun_user['language'].'/userlist.php';
// Load the search.php language file
require PUN_ROOT.'lang/'.$pun_user['language'].'/search.php';
// Determine if we are allowed to view post counts
$show_post_count = ($pun_config['o_show_post_count'] == '1' || $pun_user['g_id'] < PUN_GUEST) ? true : false;
$username = (isset($_GET['username']) && $pun_user['g_search_users'] == '1') ? $_GET['username'] : '';
$show_group = (!isset($_GET['show_group']) || intval($_GET['show_group']) < -1 && intval($_GET['show_group']) > 2) ? -1 : intval($_GET['show_group']);
$sort_by = (!isset($_GET['sort_by']) || $_GET['sort_by'] != 'username' && $_GET['sort_by'] != 'registered' && ($_GET['sort_by'] != 'num_posts' || !$show_post_count)) ? 'username' : $_GET['sort_by'];
$sort_dir = (!isset($_GET['sort_dir']) || $_GET['sort_dir'] != 'ASC' && $_GET['sort_dir'] != 'DESC') ? 'ASC' : strtoupper($_GET['sort_dir']);
$page_title = pun_htmlspecialchars($pun_config['o_board_title']).' / '.$lang_common['User list'];
if ($pun_user['g_search_users'] == '1')
$focus_element = array('userlist', 'username');
define('PUN_ALLOW_INDEX', 1);
require PUN_ROOT.'header.php';
?>
<div class="blockform">
<h2><span><?php echo $lang_search['User search'] ?></span></h2>
<div class="box">
<form id="userlist" method="get" action="members.php">
<div class="inform">
<fieldset>
<legend><?php echo $lang_ul['User find legend'] ?></legend>
<div class="infldset">
<?php if ($pun_user['g_search_users'] == '1'): ?> <label class="conl"><?php echo $lang_common['Username'] ?><br /><input type="text" name="username" value="<?php echo pun_htmlspecialchars($username) ?>" size="25" maxlength="25" /><br /></label>
<?php endif; ?> <label class="conl"><?php echo $lang_ul['User group']."\n" ?>
<br /><select name="show_group">
<option value="-1"<?php if ($show_group == -1) echo ' selected="selected"' ?>><?php echo $lang_ul['All users'] ?></option>
<?php
$result = $db->query('SELECT g_id, g_title FROM '.$db->prefix.'groups WHERE g_id!='.PUN_GUEST.' ORDER BY g_id') or error('Unable to fetch user group list', __FILE__, __LINE__, $db->error());
while ($cur_group = $db->fetch_assoc($result))
{
if ($cur_group['g_id'] == $show_group)
echo "\t\t\t\t\t\t".'<option value="'.$cur_group['g_id'].'" selected="selected">'.pun_htmlspecialchars($cur_group['g_title']).'</option>'."\n";
else
echo "\t\t\t\t\t\t".'<option value="'.$cur_group['g_id'].'">'.pun_htmlspecialchars($cur_group['g_title']).'</option>'."\n";
}
?>
</select>
<br /></label>
<label class="conl"><?php echo $lang_search['Sort by']."\n" ?>
<br /><select name="sort_by">
<option value="username"<?php if ($sort_by == 'username') echo ' selected="selected"' ?>><?php echo $lang_common['Username'] ?></option>
<option value="registered"<?php if ($sort_by == 'registered') echo ' selected="selected"' ?>><?php echo $lang_common['Registered'] ?></option>
<?php if ($show_post_count): ?> <option value="num_posts"<?php if ($sort_by == 'num_posts') echo ' selected="selected"' ?>><?php echo $lang_ul['No of posts'] ?></option>
<?php endif; ?> </select>
<br /></label>
<label class="conl"><?php echo $lang_search['Sort order']."\n" ?>
<br /><select name="sort_dir">
<option value="ASC"<?php if ($sort_dir == 'ASC') echo ' selected="selected"' ?>><?php echo $lang_search['Ascending'] ?></option>
<option value="DESC"<?php if ($sort_dir == 'DESC') echo ' selected="selected"' ?>><?php echo $lang_search['Descending'] ?></option>
</select>
<br /></label>
<p class="clearb"><?php echo $lang_ul['User search info'] ?></p>
</div>
</fieldset>
</div>
<p><input type="submit" name="search" value="<?php echo $lang_common['Submit'] ?>" accesskey="s" /></p>
</form>
</div>
</div>
<?php
// Create any SQL for the WHERE clause
$where_sql = array();
$like_command = ($db_type == 'pgsql') ? 'ILIKE' : 'LIKE';
if ($pun_user['g_search_users'] == '1' && $username != '')
$where_sql[] = 'u.username '.$like_command.' \''.$db->escape(str_replace('*', '%', $username)).'\'';
if ($show_group > -1)
$where_sql[] = 'u.group_id='.$show_group;
// Fetch user count
$result = $db->query('SELECT COUNT(id) FROM '.$db->prefix.'users AS u'.(!empty($where_sql) ? ' WHERE u.id>1 AND '.implode(' AND ', $where_sql) : '')) or error('Unable to fetch user list count', __FILE__, __LINE__, $db->error());
$num_users = $db->result($result);
// Determine the user offset (based on $_GET['p'])
$num_pages = ceil($num_users / 50);
$p = (!isset($_GET['p']) || $_GET['p'] <= 1 || $_GET['p'] > $num_pages) ? 1 : $_GET['p'];
$start_from = 50 * ($p - 1);
// Generate paging links
$paging_links = $lang_common['Pages'].': '.paginate($num_pages, $p, 'members.php?username='.urlencode($username).'&show_group='.$show_group.'&sort_by='.$sort_by.'&sort_dir='.strtoupper($sort_dir));
?>
<div class="linkst">
<div class="inbox">
<p class="pagelink"><?php echo $paging_links ?></p>
</div>
</div>
<div id="users1" class="blocktable">
<h2><span><?php echo $lang_common['User list'] ?></span></h2>
<div class="box">
<div class="inbox">
<?php
// Grab the users
$result = $db->query('SELECT u.id, u.username, u.use_avatar, u.title, u.num_posts, u.registered, u.jabber, g.g_id, g.g_user_title, g.g_title FROM '.$db->prefix.'users AS u LEFT JOIN '.$db->prefix.'groups AS g ON g.g_id=u.group_id WHERE u.id>1'.(!empty($where_sql) ? ' AND '.implode(' AND ', $where_sql) : '').' ORDER BY '.$sort_by.' '.$sort_dir.' LIMIT '.$start_from.', 50') or error('Unable to fetch user list', __FILE__, __LINE__, $db->error());
if ($db->num_rows($result))
{
while ($user_data = $db->fetch_assoc($result))
{
if ($pun_config['o_avatars'] == '1' && $user_data['use_avatar'] == '1' && $pun_user['show_avatars'] != '0')
{
if ($img_size = @getimagesize($pun_config['o_avatars_dir'].'/'.$user_data['id'].'.gif'))
$user_avatar = '<img src="'.$pun_config['o_avatars_dir'].'/'.$user_data['id'].'.gif" '.$img_size[3].' alt="" style="float: left" />';
else if ($img_size = @getimagesize($pun_config['o_avatars_dir'].'/'.$user_data['id'].'.jpg'))
$user_avatar = '<img src="'.$pun_config['o_avatars_dir'].'/'.$user_data['id'].'.jpg" '.$img_size[3].' alt="" style="float: left" />';
else if ($img_size = @getimagesize($pun_config['o_avatars_dir'].'/'.$user_data['id'].'.png'))
$user_avatar = '<img src="'.$pun_config['o_avatars_dir'].'/'.$user_data['id'].'.png" '.$img_size[3].' alt="" style="float: left" />';
}
else
$user_avatar = '';
$user_title_field = get_title($user_data);
?>
<div style="margin:5px">
<h2><a href="<?php echo "profile.php?id=" . $user_data['id'] . '">' . $user_data['username']; ?></a></h2>
<p style="float:right"><?php echo "<b>" . $lang_common['Registered'] . "</b>: " . format_time($user_data['registered'], true); ?></p>
<?php echo $user_avatar; ?>
<?php
// The CS nick is stored in the Jabber column. Who uses that anyways? :P
$cs_nick = ($user_data['jabber']) ? $user_data['jabber'] : "None";
echo "<b>" . $lang_common['Title'] . "</b>: " . $user_title_field . "<br />\n<b>" . $lang_common['Jabber'] . "</b>: " . $cs_nick . "<br />\n<b>" . $lang_common['Group'] . "</b>: " . $user_data['g_title'] . "<br />\n<b>" . $lang_common['Posts'] . "</b>: " . $user_data['num_posts']; ?>
</div>
<div class="clearer"></div>
<?php
}
}
else
echo "\t\t\t".'<tr>'."\n\t\t\t\t\t".'<td class="tcl" colspan="'.(($show_post_count) ? 4 : 3).'">'.$lang_search['No hits'].'</td></tr>'."\n";
?>
</div>
</div>
</div>
<div class="linksb">
<div class="inbox">
<p class="pagelink"><?php echo $paging_links ?></p>
</div>
</div>
<?php
require PUN_ROOT.'footer.php';
?>
