If this is a public patron ticket paid event, you will have to get your liqueur licence organised firstly, and the police will be also involved in that process, whicht can take months of mucking around, unless you have very powerful friends in high places.....
http://www.police.gov.hk/hkp-home/en...r(eng)-apt.pdf Looks like you'll already need a permanent liqueur licence firstly, and then need to apply 12 days before an outdoor public event, for a temporary outdoor alcohol permit....
Good luck if you don't have a licence compliant permanent venue... Might be smart to use the captive catering situation at Cyberport, but you'll still need whoever is licenced, to apply for a public outdoor permit, 12 days before the event.
I wouldn't say Hong Kong is all that RAVE party friendly, lots of nanny state rules regarding this socially, but a large warehouse somewhere, might be a better option, or better still, an aircraft hangar maybe at Shek Kong lol, but you will have a list of duty of care, insurance, security staff paper work a mile long to chase through...
I seriously doubt your chances....