If this is for 'specific products', then you can code for those products uniquely, perhaps something like this:

in html_header.php
Code:
/**
 * load the module for generating page meta-tags
 */
require(DIR_WS_MODULES . zen_get_module_directory('meta_tags.php'));

// set cookies unique to certain products:
if ($current_page_base == 'product_info' && $_GET['products_id'] == '32') {
   // do code here to set cookie
}

/**
 * output main page HEAD tag and related headers/meta-tags, etc
 */
?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" <?php echo HTML_PARAMS; ?>>