Login to your admin account as Adam explained above. Then go to Store » shipping » under “Custom Options”, choose “use custom”, “domestic shipping” and “free ground shipping”.

Then on the checkout,use this jQuery:

<script type="text/javascript" charset="utf-8">
$(document).ready(function(){
//If weight is less than 150, hide the option for shipping billed later
jQuery("#fc_shipping_methods_inner").ajaxComplete(function(event, request, settings) {
if (fc_json.total_weight < 150) {
$("label[for='shipping_service_60']").addClass('hide');
}
});
});
</script>

For removing:

$("label[for='shipping_service_60']").remove();
}

• http://forum.foxycart.com/comments.php?DiscussionID=4076&page=1#Item_7