You could just use a bookmarklet and javascript to replace all of the forms' action attributes. That way your developer can do it with one click instead of changing urls.
Something like this will prefix all form actions on the page with "/outputPOST".
javascript:(function(){var forms=document.getElementsByTagName('FORM');for(i=0;i<forms.length;++i){forms[i].setAttribute('action','/outputPOST'+forms[i].getAttribute('action'));}})();