Not sure if this is solved in drupal 7, but in drupal 6 you surely need to override
views-view-summary-unformatted.tpl.php with custom code. More on this you can find here
http://drupal.org/node/403012 but I did my own fork that looks best for my needs and think is the best out of those offered on link above. Here it is
<?php
$total = 0;
$letters = range('0', '9');
$letters = array_merge($letters, range('A', 'Z'));
// $letters = array_merge($letters, range('!', '/'));
foreach ($rows as $id => $row) {
$existing_letters[] = $row->link;
$urls[$row->link] = $row->url;
$counts[$row->link] = $row->count;
$total += $row->count;
}
$letters[] = "SVE";
$existing_letters[] = "SVE";
$urls['SVE'] = str_replace(strtolower($row->link), "sve", $row->url);
$counts['SVE'] = $total;
foreach ($letters as $letter) {
$active_class = '';
if (arg(1) == drupal_strtolower($letter)) {
$active_class = 'active';
}
if (in_array($letter, $existing_letters)) {
$nav[] = '<span class="views-summary views-summary-unformatted result"><a href=' . $urls[$letter] . ' class=" ' . $active_class . '">' . $letter . '</a></span>';
}
else {
// commented out for displaying chars with no results $nav[] = '<span class="views-summary views-summary-unformatted no-result" class=" ' . $active_class . '">' . $letter . '</span>';
}
}
print implode(' ', $nav);
?>