First step is pulling the main PCB out of the ECM's frame.
Lot easier to do the needed modifications when I had total access to the PCB.
Here is the bottom side of the new daughter board.  Nothing too exciting.  Just a bunch of wires.
Here is the topside view.  A little sizing of the proto board to get into place.   Luckily the ECM's frame has bosses that I was able to drill and tap into to mount this guy.
Little tedious striping to length and soldering the address and data lines to the ribbon cable.  One mistake would lead to the big boom.  A bad solder connection could leave you stranded, so take your time.