Calling SOAP WebService with JavaScipt, prototype.js, and ws.js failing in IE 10

I have a JavaScript application that's calling a SOAP web service.  I've been using prototype 1.7 and ws.js to make the calls to and from the service for years.  Now, we're getting calls from people with IE 10 that the web service is failing.  

It's failing in ws.js on the following line:
SOAP.Envelope.prototype = (new SOAP.Element()).extend({

The error says, "Object doesn't support property or method extend"

Googling around I found an article http://www.ibm.com/developerworks/forums/thread.jspa?threadID=216588 that talks about getting ws.js to work with prototype 1.4 or higher.  However, I made the changes outlined there:

// instead of using .extend (no longer supported)
//SOAP.Header.prototype = (new SOAP.Element()).extend({

// we extend the SOAP.Element
Object.extend(SOAP.Header.prototype,SOAP.Element.prototype);

// and then extend the SOAP.Header interface
Object.extend(SOAP.Header.prototype,{

But I and get another error: "Unable to get property 'prototype' of undefined or null reference"

So, I have two questions:

1. What do I need to do to get prototype 1.7 and ws.js to work together?
or
2. Is there a better way to call a SOAP web service than with prototype and ws.js?