Add remoteUser in browser portlet uri as a parameter like 'http://blah.com&userId=joe23'

 Does anyone know how to add the user to the uri like that? I was looking at the portlet.xml but it seems to only allow netuix tags. Has anyone done this with a backing file or similar mechanism. 

I think I need the browser portlet because I want the conversation to continue as normal without any relay or forward required after the initial uri redirect.

The username is required on the url to the third party web application.