That url is the WSDL for the publishing engine, I'm not sure what other services you think it's for. I've used that WSDL to create requests to the PE using a tool like Soap UI. The last time I tried it, I couldn't get a correct response from the PE so PTC might have unknowingly broken the service. It worked in 5.4 for us, but not in 6.0.
Alternatively, you can use URLs to get request/response for PE composition. Here's an example URL:
You can add multiple parameters to the end of the request, they are documented in the help. Here's some examples:
Hope this helps.
Sounds like a fairly difficult person to work with, I don't understand why they can't create their own SOAP UI project for this.
Are you familiar with SOAP UI? It's a free program you can download. Once installed, you can create a new project, pointing it to the WSDL for your PE:
It will automatically create XML to send a request to your PE. From there you can fill in the XML with the parameters needed. The project you create will be an XML file you can send to the tester you're working with.
I hope that helps, if you're still having trouble, I should have an example SOAP UI project around here that I could dig up.