The process by which you grant the ability to run a privileged system procedure is dependant on the security model under which it runs.
For a privileged system procedure using the SYSTEM PROCEDURE DEFINER model, grant EXECUTE privilege on the system procedure to the user:
GRANT EXECUTE ON sys_procedure_name TO grantee [,...]
For a privileged system procedure using the SYSTEM PROCEDURE INVOKER model, grant the underlying system privileges required by the system procedure to the user. Use sp_proc_priv() to identify the system privileges required to run a system procedure.
GRANT system_privilege_name TO grantee [,...]