What exactly are you trying to do? I’m no expert here, but in general, dvd recorders are not designed to directly interface and or be controlled by a computer. The fireware port is designed to interface with a camcorder (I have no Idea if it can interface directly with a computer but I have never heard of a dvd recorder doing that). If you are trying to capture video from dvd or vhs to your computer or record video from the computer onto the recorder, there are probably ways to do it (may require aditional hardware depending on what you want to do and your computer).
What are you trying to do?