Load Testing of Client server application involving Java Swing & Web Services

I want to perform load testing on a client server application involving Java Swing & Web Services. However I'm not able to record the script using VUGen. What is the protocol that needs to be selected and are there any other settings required ?
Following are the details of application:
Client : JAVA swing UI ( The client is lauched using Java Webstart - either from command line or from browser)
Server: Websphere Application Server
Communication using SOAP-XML .