I also have only moved freshwater fish before, but most of the principals are the same.
1. Minimize stress. Either transport the fish in a large container with a battery-operated air pump, or pack them individually in bags like they do at the pet store. Some pet stores will do this packing for you, make this your last task in moving. Keep the temperature constant, putting the bags in a cooler might be a good idea, use heat or cold packs as necessacary.
2. Minimize time in transport containers. Find a way to keep your fish comfortable as possible up to the moment of departure and as soon as possible after arrival. There may be alot of work involved with taking down and setting up thier tank; they may benifit from moving to a temporary container (such as a rubbermaid bin,) with thier own tank water and an airstone, on both ends of the trip. Bottling thier water and taking it with you may be a big help.
One of the big problems with salt that I don't have with fresh, is mixing up the saltwater. Since we're supposed to let the salt water mix for 24 hours before use, you can't just top off the tank with whatever water is available. Bottle as much of the old water as you can, and use it for a temporary container while the full tank-full of salt water is getting ready. Make sure you have enough salt to make up a tankful of water with you.