No owner's manual and Haynes doesn't list 92 Metro fuse panel usage to identify diagnostic socket for ODB-I emissions testing so how do you activate the ODB-I system?

If you'll look under the steering wheel side of the dashboard, you should see the connector. You can use a paper clip and insert it into the holes on the extreme right side of the plug. The holes you put it in are the two on the right side,one on top of the other one. Once you do this, just turn the key on and read the pulses on your check engine light.