How do you install a starter for a 1992 Chevy Lumina v6 3.1?

You'll need to lift up the car and support it on at least one jack stand. Disconnect the positive terminal of the battery. Remove the oil filter (make sure a drain pan is underneath). There are two bolts that hold the starter to the engine/transmission. (15mm I think) These bolts are vertical; it helps to have a wobble-extension to get them out. After it's loose, disconnect the positive battery lead and the ignition signal lead from the solenoid. (there is another nut on there grounding the solenoid to the starter - don't mess with it; you'll be removing them together). After your two nuts have been removed and the wires moved away, slide the starter over and out around the a/c lines through the space where the oil filter used to be. Mine had a shim on the top of the starter, but the aftermarket starter from the parts store was made to be used without it. Make sure you know whether or not your new starter needs the shim.

Additional info

It is generally easier to remove the starter if you disconnect the electrical connections [battery lead and ignition lead(s)] before taking out the starter bolts. This prevents the weight of the starter from pulling out the wiring and also makes it easier to move around in such a tight space.