vCO SOAP plugin version 1.0.0. does not support preemptive authentication which might result in 401 error.
The latest version of the plugin is 1.0.1 unfortunately also does not support preemtive authentication
Preemptive authentication will be availabe in version 1.0.2 of the plugin. You can contact VMware Global Support Services and they should be able to provide you with a version of the plugin containing the preemptative authorization.
Regards Ivo