To get the GPS data out the IR port, you *could* use IrCOMM (serial over IrDA), but Cushman's worked on this and said it's not very reliable.

The easier way would be to split the incoming serial data into discrete messages and use IrOBEX to send one message at a time out the IR port. I believe one of the goals of Empire was to allow bi-directional IR traffic. You'll prolly wanna talk to Cushman and ask what you need to do so you can write a module for Empire.