Okay I'll give this a shot. I suggest filling out your veichle profile portion so we know what year tib you drive.

RD1. Leave your 02 sensor where the stock one is. There should be a bung there with no problems reaching it. Right before the cat. For your 2nd sensor put a bung there or have a shop do it and place your 02 sensor right after your cat. You might need to extend the wires. Simplest way is this. Take your shifter plate and radio suround off. To the right of the shift cables you will see a gromet with wires going down under the car. That's where your 2nd 02 sensor is. There's also a plug there. Unplug it, take the gromet through and slide the plug through the hole where the gromet was. Now unbolt your 02 sensor. Once it's in your hand cut the wires making sure you still have enough wire on the plug side to make the connections with the new wires. Now grab the plug and go visit an electrical store. Show the guy what wires you need and he'll do the work for you. If not make sure to match up the wire guage wise and also how they look inside. Once you have the wires solder them to the ends of the plug and the ends where the 02 sensor is. Make sure you cover the exposed wire and now install. If you have and rd2 have your first sensor in the first bung on the obx headers right by the exhaust ports and plug the one on the down pipe. The rest is the same. Hope this helps.