sudo screen /dev/ttyACM0 115200To disconnect, press [Ctrl][A], followed by [k], and respond [y].
I wanted to watch boot sequence, but the USB does not come online until the end of the init process. I had purchased a USB to serial adapter, but did not find an obvious path between the "Prolific Technology PL2303" converter, and the serial header on the BeagleBone. The lack of documentation should not have been a surprise: most people have no interest in this feature.
To make matters more interesting, the picture on the Adafruit website was off by one pin:
Christophe Blaess, who had posted a picture of the correct pin-out: