The ECU in a Cobalt is already listening to the AC Pressure Sensor, and is able to send this sensor's voltage on the high speed GMLAN which is GMs early version of the CANBUS system.
HP Tuners VCM Scanner software can monitor AC Pressure Sensor Voltage via the GMLAN on the OBDII port.
If you hook that AC sensor wire up to a wideband O2 sensor, then the voltage can be used by the software. I would check the voltage range of the original AC sensor and be sure that wideband sensor is in the same voltage range. Hopefully they are both 0-5v sensors.
VCM Scanner is used to gather log files while your engine is running.
This data is then used to modify the tables in your ECU, by using VCM Editor.
You could write a user defined math parameter named "wideband" that uses the voltage from the AC Pressure Sensor, and that can become part of your graphs.