I just called CO Customer Cares, who referred me to the OP Serice Center. Both mentioned that invitations were sent to 'select' Platinum members, so if you didn't receive it you are out of luck.
BUT, the OPSC agent did tell me the time & location of the ceremony at EWR tomorrow: 10 am Termiinal C near Gate 103 , so if anyone wants to be a gate crasher--
As my flight doesn't leave until 7:20pm, I don't think I'll make it.