I don't think you really want to do this.
You can setup many ROLES in Alfresco and users can be members of none or more of them.
When you try to do something in Alfresco such as view a space that has had permissions set against it, it will check if your user is mentioned specifically, or if your user a member of any ROLE assigned.
So, at anytime, your user can be a member of multiple ROLES and I don't think you want to list these in your header.
Regards
Steve