M’O Tickets/passes are easy to come by. Getting into the museum is harder. In 2012 and previous years mere ticket holders still had to queue up prior to even getting into the Lobby.
Wheelchair visitors seem to be able to “jump the queue” and enter the Lobby ahead of other visitors. I hope that will always be true. I don’t have limited mobility, so I tried another technique to avoid the queueing up process. Once you’ve gained entry into the Lobby, you can either present your current visitor pass to the gate keepers, or purchase your pass/ticket for the day. There was(is?) another ticket possibility that worked for me, but I had an extended Paris stay and planned on subsequent visits. I joined the Museum. I did the same thing at the Louvre, but that’s another story (“Sticking” to the Louvre“). As an “adherent” you get to use the members’ door and avoid a long visitor’s queue.