Tim,
In order to consume a SOAP API I recommend you use something other than JavaScript.
Any platform can offer you a good SOAP client should be OK. (.Net, Java, php, Ruby, python).
I didn't see anyone successfully used javascript and consume the Eloqua SOAP API.
I know you can create a SOAP client in Java script but it will be too much work to handle the Eloqua response in some cases.
Regards,
Daniel