Hi again Tony,
The Multiple Audio Interfaces movie is number 7, I believe.
Anyway, here's the steps for configuring Aggregate Devices:
1. Connect your X-Station to your Mac (yeah, I know, stating the obvious).
2. Go to the Utilities folder, and launch Audio MIDI Setup.
3. Click on the 'Audio Devices' tab at the top of the Audio MIDI Setup window.
4. From the Audio menu, choose 'Open Aggregate Device Editor'.
5. Click on the + sign below the upper window, to add a new aggregate device.
6. Rename the new aggregate device if you want to.
7. The lower window shows all available audio ins/outs - in your case it should show Built-in Audio (2 in 2 out), and X-Station Audio (2 in 2 out).
8. Check the 'Use' box at the left of both of these.
9. Then click 'Done' to close that window, and quit Audio MIDI Setup.
10. Launch Ableton Live, and go to the Preferences/Audio tab. Choose the new Aggregate Device as your Audio Output Device.
11. Click on the Output Config button below the Audio Output Device to see teh list of available outputs. Disable the mono outputs, and activate 1/2 (stereo) and 3/4 (stereo). Click OK to close this window, then close preferences.
12. Choose View In/Out. From the bottom of the Master track, you can choose Cue Out and Master Out. Click on either of these boxes, and the stereo pairs from your Aggregate Device will be available.
13. If your setup works the same as mine, 3/4 will be your master stereo output, and 1/2 will be your cue output - plug your headphones into your Mac's headphone output to prelisten.
- As far as I can tell, it's not possible to route the Cue to the XStation headphone out if you're using the XStation as your main stereo out.
Hope that all helps! :-)