as far as I remember it will be like this:
In item.php replace
<?php while ( osc_has_item_meta() ) { ?>
<?php if(osc_item_meta_value()!='') { ?>
with
<?php while ( osc_has_item_meta() ) {
$show_custom = (osc_item_meta_value() == '' || strpos(osc_item_meta_value(), 'cross.png') ? 0 : 1);
if ($show_custom) { ?>