I know this is literally the most trivial bug, but it's also missing on my 3rd Gen.
I noticed that in the source 3G config file, there was no "HAVE_HARDWARE_CLICK" defined. I added this, but it failed to compile. I included piezo.c and got it to compile, and the speaker keyclick option is now on the iPod, but unfortunately it doesn't work.
This is above my skill set I'm afraid.