I'm still a little confused on exactly what you mean.
If you want to use your console faders to control and write automation within Sonar that is relatively straightforward.
You can use ACT or better still "Mackie Mode" if your console supports the Mackie protocol. Make sure it is installed first as a MIDI device, Preferences---->MIDI---->Devices, and then as a control surface Preferences--->MIDI--->Control Surfaces. One advantage of Mackie mode over ACT is that motorised faders will respond to Sonar faders in Mackie mode. In ACT mode they don't, ACT is a one way communication protocol, the Mackie protocol is two way.
Once that is done your faders on the console will correspond to Sonar's track and buss faders in banks of 8 or multiples of 8 depending on exactly how it is set up. There should be some way to shift bank focus on your controller, if not use the coloured WAI (Where Am I) strip that appears beside the tracks in TV or beneath the strips in Console View.
All you have to do then is arm the tracks for "automation write" and move faders on your console while playing back the project.
Fader movement will be recorded as automation. Behaviour will depend on the "Write mode" chosen in the "Track Properties". Find that using the "Track tab" of the Inspector.
If you want to mix OTB at the same time that may vary by system but on mine I can only mix 16 channels at a time (because that's all I have on the console - an Allen & Heath ZED-R16 btw)
Here's how I do that I guess your set up will be something similar.
Assign 16 track (or buss) outputs within Sonar to the 16 individual channels on the ZED.
Sonar track 1 output--->ZED channel 1
Sonar track 2 output--->ZED channel 2
etc. etc.
Set up the routing as required on the console. I can choose to have the audio come into the console just after the pres and run the full strip or have it come in post EQ, so it just uses the aux sends (for outboard FX) & faders.
Now the console is processing each of Sonar's tracks/busses.
From here there are choices.
Re-record back into Sonar, Sonar needs to be in record mode rather than playback for this to happen though, or record to an external device using the console main or aux outputs.
There are further choices if re-recording back into Sonar. Either on an individual track basis back a new lane on the track being processed, or a completely different track by setting the Sonar track inputs accordingly. Alternatively record the summed stereo two track on the console L-R buss by selecting that as an input to a Sonar track.
Obviously there is some configuration to do on the console as well but that will be specific to your set up. A little more info on that might help if you need more advice/help.