You could try this:

/includes/templates/YOURTEMPLATE/templates/tpl_modules_products_all_listing.php
lines 22-24 have:
PHP Code:
  if ($products_all_split->number_of_rows 0) {
    
$products_all $db->Execute($products_all_split->sql_query);
    while (!
$products_all->EOF) { 
change to:
PHP Code:
  if ($products_all_split->number_of_rows 0) {
    
$products_all $db->Execute($products_all_split->sql_query);
    
$row_counter 0;
    while (!
$products_all->EOF) {
      
$row_counter++; 
line 114 contains:
HTML Code:
    <tr>
change to:
PHP Code:
          <tr class="<?php echo ((int)($row_counter/2)==($row_counter/2)) ? 'productListing-even' 'productListing-odd'?>">