I am doing it on an RB26, and yes it is the bosch sensor (I have my own new one, not using the cars sensor) which is the round ones with the hole and as you say it is essentially a mic. I have had it work in the past through the stereo aux in as an experiment and worked quite well.
I am definately pickign up vibration and the issue is there isn't much availble space on the block to place a tube, I am going to possibly put the car on the ramp if the knock sensor doesn't work well on the laptop but yesterday I did try to listen to the sensor using a mini diy amp and I could hear the engine but had a lot of noise from alternator and ignition as it was powered of the cars battery. I am hoping it will be clearer on my laptop as it was very clear when I did it on the aux in on my radio a few years ago.
will let you guys know how I get on.
And for those that don't know what det cans are you can google them but they are used to hear the engine for detonation when mapping.