Just like in the passing from Tiger to Leopard, Apple again modified the procedure allowing the activation of the Root account by removing the utility: Directory Utility. To find it, it is now necessary to go in the preferences system "accounts" , to click on Options, then - network account server - and then finally to click on "Open Directory Utility".
The procedure is then identical to that of Leopard. Another solution is to go to: System/Library/CoreServices.Directory Utility is inside. You will be able to make alias of it if you have need to use it at other times.
