This quick technote details the CIS-E wiring harness, as found in a 1987 VW Scirocco. This should be similar for any 1.8L 16v.
This picture shows the whole harness with everything labeled.
This picture shows the Oxygen Sensor connectors, the green is the sensor, the two pin is for the oxygen sensor heater
This picture shows the wiring of the hall sender. This is useful because these wires break often. Megasquirt also can connect to this using the color codes.