Voxengo Span setup for multiple inputs

Hey guys, I'm trying to setup my speakers properly in my home studio and seen a tutorial on youtube using Voxengo Span to compare pink noise running through sonar, to that which is coming through your speakers.They seem to have the plugin on the master and a mic track picking up the audio and routed into an input on Voxengo Span In the tutorial they don't explain how to set it up and says its a bit tricky. I found a tutorial on how to do it in other DAW's but couldn't figure out how to do it in Sonar?? Here's the link of what he's doing  it starts at the 8:54 mark. Any help would be awesome thanks!