EPCS is the pet project of an unknown individual(s) with a significant amount of influence and money. They totally converted an asteroid hurtling between solar systems into a moving party station. There is no admission cost or money involved inside the asteroid, so the only limit to admission is finding and getting to EPCS. The easiest way to find it's current location is to be a member of the galactic elite, as it is said that someone in the high echelons always knows where it is. The flight trajectory changes randomly, so the only way to accurately locate it is to find a source. There are many rumors of sources outside of the elite, but the majority of people who say they know where it is are either wrong or lying in order to send you to a more unscrupulous location.
If you manage to actually make it to the asteroid, your ship is automatically docked and everyone who wants to stay on EPCS gets off and has a full spectrum scan, as well as a chip implanted in their spine if they do not already have a neural net. The chip, or neural net, allows the person to automatically upload their consciousness to the asteroid once an hour. If something happens to the individual during their time on EPCS that results in grievous injury or death, as is often the case with extreme partying in the 4th millennium, the person is simply regrown and their memories are implanted from the back-up. Patrons who are in the throes of the asteroid do not need to worry about death, and thus experience an even freer and more enjoyable time than they could have otherwise.