I think you are correct that the tire pressure monitoring system was discontinued after 97. And I think you are correct that the DIC's dont interchange (sorry to say).
You also have to be carefull with "trac" / "tcs" button. The "trac" will be for GT's and "tcs" is for GTP's. From what I hear the two are not interchangable.
Flashing 0's mean the unit is missing its data signal. Download the connector schematics in the first post and see if all the wires in your plug are in the correct places. You may be able to change some pins around in your plug to make it work.