Hey guys, got this running, but was seeing some randomness in the serial responses, missing text, odd line breaks. I've got it running very smoothly now, but you have to disable linux from using ttyAMA0 for getty and kernel messages.
You'll want to run
to disable getty on startup
and edit /boot/cmdline.txt and remove any references to ttyAMA0 or serial0
there's also this script, https://github.com/lurch/rpi-serial-console
which I have not tested.