This is not so much a command as it is a privilege. As a Level 1 and Level 2 Member Plus, you may have noticed that you were unable to enter rooms that were listed as full (with the exception of Tournament rooms). Well, as a Level Four Member Plus, you will have the ability to enter a room that is already filled to capacity.
Entering full rooms is a useful privilege for Member Pluses in that you can assist players who request help, but are in a room that has reached its capacity. As a Level Four Member Plus, if you so choose, you will be able to provide players in full rooms the help or assistance they need!