Replacing Oxygen Sensors

Does anybody know what is involved in replacing the o2 or oxygen sensors on a 1998 Prelude SH ? Also how do you check to see if they need replacing ? Front sensor .... rear sensor ? Is this done just by the code reader ? Is this more difficult and/or time consuming than a timing belt/water pump replacement ? Thanks...

replacing o2 sensors is easy. just buy the special socket from any automotive store, unplug the sensor and screw it out. of course you have to have the car off the ground and be able to get at the sensor. as far as checking if there bad, i'm not sure about that. oh, but when you put the new sensor in, you want to make sure and not touch the sensor part to anything, and it's also a good idea to put antisieze on it. that helps a lot if you ever need to take it off. good luck