Send it to your press list by fax or e-mail, and then follow up by phone. Stress the need for the event and pitch a larger story to key journalists.
You can also get a member of the media involved as the master of ceremonies to ensure more coverage. Just be sure the media person is from a major press outlet that will reach the right people for you.
Send out a second release closer to the date that publicizes the event from a slightly different angle, and follow that up with phone calls as well.
In addition, you can put together a support team and give each person a certain number of tickets to sell. Talk with local businesses about buying tables or taking sponsorships and acknowledge them in your program. Good luck!