It looks harder than it is.
All you really have to do is right click on the fader knob in Console view and select Read enabled + Write enabled, then make your adjustments in real time the way you want the volume changes to be.
After you are done with these changes, Make sure to turn off Write enabled. (but leave Read enabled on).
What it does is it records fader movements. This goes true for other parameters in Sonar as well like panning, mute, exc.
Its probably one of the greatest features of the digital audio workstation since its inception.
If you have any problems let me know.