Using NuSOAP you only need a wsdl address, and then the NuSOAP will handle the rest of this. It fully compatible with PHP4. So, this should be an easy task. As you find on my feedback, I am expert in NuSOAP. Anyway, considering the web service you described here using wsdl which is presented under https protocol, it will need a valid credential. And once again NuSOAP presents this issue resolution also. So, let's do it, I am ready for this job.