Maintaining Session

I am using IB to send soap webrequests to a vendor application.Two webservice methods needs to be called in sequence which runs on two different soap threads.

1) Need to call a vendor webservice method login which establishes a session and returns a session ID in the response message

2) Need to call insert method to perform business operations.

When i call the insert method my session gets lost and cannot proceed further as the session which gets established in step -1 is lost when i perfrom step -2.

Any help is highly appreciated on how to get the session ID for a soap web requests in the TCL script ?