I did a similar integration with IBM Maximo where you had to send a SOAP Web Service request to login and get a session id back then you would use that session id to do the next SOAP Web Service call. What I did was create a business rule to watch the ECC Queue for when the login response came back then kicked off the next SOAP Request. Then another business rule to watch for the response of that to process what I needed. I didn't use Runbook to do any of that but maybe someone else has.
