I've added CV as well as Gate / Trigger output to the Octo DAC setup. Note-on events will trigger a gate on, while note-off events will trigger a gate-off. The eight DAC outputs remain the same. Each gate output has a dedicated digital pin on the Teensy 2.0.
Download the code here: http://milkcrate.com.au/_other/downloads/arduino/MCP4922_DAC_GATE/