I would (and did) mount it on the drivers side, Pre-cat if you can. If you have a catless or high flow, 2 cat pipe you can use the 2nd set of bungs and shut off the rear o2 sensors in the tune. Most of the kits come with a weld in bung if you chose to use that. Ideal position is between 10-2 to keep the sensor out of condensation and helps protect the sensor itself.
I wouldn't worry about installing it pre-cat too much or installing the bung if you have a hand held. Heck, the dyno tuners use a sniffer at the tail pipe of the car and will either use that, or both when tuning.
EDIT...Eh, then again i just realized im in the 94-95 forums :tongue3: