Thanks very much. The updated instructions work and my clock is now happily hacked. I still haven’t got the FTDI cable to work on the Mac, nor got the code to compile on the Raspi. But by exporting the binary on the Mac and uploading it to the Alpha Clock 5 via the command line on the Pi, I have achieved the result that I’m looking for.
I’m very grateful for your quick response. Keep being both evil and mad.