Same as title.

Why the hell did the 2nd Gen have them??

umm why would you want to and they were a different efi control system thats why they had them

umm why would you want to and they were a different efi control system thats why they had them
They want to because the 2nd gens could automatically advance timing to take advantage of higher octane fuels and get more power and torque out of the engine.
The control system for this would probably be encorporated into the ECU which means haha no chance! As well as the physical gears etc. that would be required to do it.
IF you want it so badly, just advance your timing and run premium unleaded all the time.

Short answer - No

Long answer - Yes it is possible if you know wtf your doing or your willing to spend money to get someone else to do it, but for the time and effort/money spent you'd be absolutely wasting your time. Knock sensors don't allow you to run more advance, they protect your engine by retarding it when it encounters bad fuel.

2nd Gens had them because they had 10:1 compression whereas 3rd gens(-ralliart) have 9:1.

Matthius

umm far as i know it wont advance timing it will only retard it when a ping or knock is picked up

Why would you want to anyway. I hated it in my Gen III, on a hot day it was so sluggish cause of the heat in the engine bay, and the timing being retarded so much cause of it.

I say take them away and just tune you engine safely, on a hot day so it never pings or even worse knocks.