I'd reccomend you find an ETCP certified rigger.
http://etcp.plasa.org/cert_technicians/search.php
it's advisable they be fully insured, and perhaps that you, the venue, and any other interested parties be listed as additional insured on the policy.
I've taken to requiring that CLIENTS add ME to their policies, too. Why should I not receive some indemnity for their physical structure's issues or negligence on the client's part? This has created some very interesting discussions that, when the lawyers talk about it, gets expensive.
@Brian - the design of any suspension system should be done by a Registered Professional Engineer, with stamped (his/her registration stamp) drawings and instructions to the contractors. The rigger is the person who then supervises/performs the lift and the attachment of the load to the provided structure.
The ETCP is a good source of certified technicians. Note that ETCP rigging certs for theater rigging and arena rigging are different; theater rigging deals more with the fly system, arena rigging is more about temporary suspension from existing structural components. My initial thoughts are to consider an arena rigger first. If the rigger is affiliated with an IATSE Local, call its business agent and have a chat about the prospect and specifically inquire as to his/her experience in facilitating permanent installations.