The tutorial is here. An excerpt follows:
This video shows how to use Expert Sleeper's Silent Way Voice Controller with Numerology. The Silent Way group of plugins allows you to use a "DC capable" audio interface as a CV control source for analog synthesizers. There are a number of advantages to this approach:
Easy, reliable oscillator calibration for better tuning overall.
When generating CV values for automation, you are no longer limited to the 127 steps of MIDI CC messages. This allows you to generate very smooth and accurate control values.
You do not have to worry about "saturating" a hardware MIDI interface by sending it too many messages at once.
As of version 2.2, Numerology provides integrated support for Silent Way by including direct hardware audio input and output routing in the module. This makes setup very quick, as you don't have to create separate I/O channels to route audio around, as you do in some other hosts.