This is how I was able to setup RTC 5.0.2 on WebSphere to allow any user in my authentication source to log in to the dashboard and create a work item.  It is painful for first time support users to first need to be imported, assigned a license, and added to a project area before they can submit a support ticket.  With this solution, a user can go directly to the support project area on a repository they have never logged in to, and create a work item.

It comes down to 4 configuration settings
1) Set your JazzUsers role mapping in WebSphere to 'all authenticated in application realm' described here:
https://www-01.ibm.com/support/knowledgecenter/SSAW57_8.5.5/com.ibm.websphere.nd.doc/ae/usec_tselugrad.html
https://jazz.net/forum/questions/208379/can-jazzusers-be-set-to-any-authenticated-user
Thanks @dnong

2) Enable 'WS Allow Self Registration' in advanced properties (I did both JTS and CCM) described here:
https://jazz.net/help-dev/clm/index.jsp?re=1&topic=/com.ibm.jazz.repository.web.admin.doc/topics/t_users_self_register.html&scope=null
Thanks @stuttle33

3) Set a default license under 'License Key Manager' on the JTS described here:
https://jazz.net/help-dev/clm/index.jsp?re=1&topic=/com.ibm.jazz.repository.web.admin.doc/topics/tmanagedefaultlicense.html&scope=null
Thanks @stuttle33

4) Set Access Control tab to 'Everyone' in the Project Area.

There is just one thing I could use some help with.  I needed to connect twice for it to work.  The first time it says I am not in the repository.  The second time just hitting reload a few seconds later, it takes me to the dashboard.  This seems like the process of self registration is taking too long.  I could not find a value in Advanced Properties that looked like it controls this.  Does anyone know if I can change something to address this?