My newly built Alpha Clock 5 sets itself! I added an Adafruit "Ultimate GPS" module, connected to the second serial port (J5) and a convenient 5V line.
The GPS module runs at 9600 bps. Normally with an Arduino I have to use an interrupt routine to capture the serial data reliably, but the processor in this clock is so fast it has no trouble keeping up with a simpler approach of just checking the port each time through the main loop.
I need to polish the code a bit, including adding setting the time zone to the menu. Once I've got everything done I'll post the mod on Github.
Next on my list: Automatic DST support!