Karen,
according to the link you provided, you could get RS-232 serial out of the gps unit using an RJ-45 connector. These are the same connectors used for ethernet connections, and you can purchase a cable that has this on one end and a nine pin serial plug on the other. You can make your own cable, but you need a tool to press the wires into the connector. You can also get PS-2 connectors, but they are harder to find and cost more. Of course you might find a broken PC keyboard, and take the cable off of it. Darrel's Instant Interrupts will be your best friend for this project.

Jerry.