Writing an Extension

Hello everyone, I am not sure if this is the right place to ask this but let me anyways. We need to write a PHP extension for the PI API (http://www.picorp.com). I have been googling and reding up stuff over the net for the last 3 days but alas not to much help. Other than ext_skel and PECL_Gen, are there any other options? What should I use? And also for the previous two, these does not seem to much information available. Can someone please throw some light on the subject? TIA Regards, Arjun