Reconfiguring BBB serial console port (ttyO0) under Ubuntu 12.04 LTS.

I am running armhf’s Ubuntu (12.0.4 LTS) on the BeagleBone Black A5C and would like to use the serial debug port (ttyO0) for general purpose communications. Consequently, I need to stop or redirect kernel/system messages and keep getty from starting up on the port. I can stop getty from starting up on ttyO0 by editing /etc/init/serial.conf and commenting out the ‘respawn’ and ‘exec’ lines. But I can’t seem to find a way to stop system messages from being output to this port. What is the best way to fix this (details please)?

Thanks for your help.