To make a small update I've been messing around with various different things to be able to achieve the goal. One of the initial problems was that the Designer actually manages to create two different SOAP addresses, one of them is the correct and secure way and the other one is direct to the data source, which would be an unsecure and blocked route. That changed things a bit when I realized that.
But still, the problem remains. If I run the script Client-Side, it works but is not an acceptable solution. If I run it Server-Side, it can't read the data and doesn't recognize the call to SOAP.connect()...
Does anybody have any experience in webb service connection with server side scripts?