Calling SOAP API through proxy with node-soap client

I am using the node-soap module and it's working fine, except when I am working behind a proxy. I can't manage to find the way to set that proxy so I can request the API.

soap.createClient(url, function(err, client) {
      client.MyFunction(args, function(err, result) {
          console.log(result);
      });
});

It's written in the docs :

The options argument allows you to customize the client with the following properties:

request: to override the request module.
httpClient: to provide your own http client that implements request(rurl, data, callback, exheaders, exoptions).

Is that the way to go?