You did not specify the OS or VCS version involved. You did use the term "root" so I will assume you are on UNIX.
1) you could use VxSS to set up secure clusters
2) you could use the halogin command (4.1) or set the AllowNativeCLIusers in the cluster (4.0)
Even with VxSS you must create accounts in VCS (no passwords) to provide the permissions for the user: Cluster Admin, Group Admin, Cluster Operator, Group Operator or Guest.