They posted about the party on this board, people asked about going, so they gave directions later on in the same post about getting an invite with specific directions.
I got my invite from just having friends on the scene, if that makes any sense. I personally didn't go through okayplayer and i'm so not in the industry, but I do think the folks on here looked out for many okayplayers and that's preety cool. My invite was first over the internet, then later on I got an email to pick up the 45 inch record(invite) in person at a hotel in Beverly Hills.