if you fully trace out the pins on your standard pc keyboard, then cut the traces on the cpc464 (assuming the board is one big pcb, and not a mombrane keyboard) and solder 2 wires to each button, and those wires to the proper pins on the keyboard encoder it should be fine. it's easier than it sounds, the tracing is just time consuming. hint: crack open a modern membrane keyboard and use different colored sharpies to trace the lines on the membranes