I'm not sure if it'll work on a 512ke, but it will on the 128k & 512k MoBos. You'll need to find a socket the same size as the 68000's and solder its legs onto the upper legs of the existing 68000. After that, you can just plug it in, Hopefully, you'll have found the drivers for the card in the meantime.

I wonder if the additional connector is to input the audio I/O of a CD hooked up to SCSI? :?: