OK. I try my best to explain what I've done to get it working.
It's late at night, three beers gone and nothing else to do
1. Get Xcode 3.2.4 from Apple Developer Network. Register for free, download the 3gig package and install
2. Get Soundflower for free, latest release. The one that worked for me is the 1.52b1 package. Install.
3. Go to the Audio/Midi Setup application and aggregate a new device with your full functioning outputs. In my case it's an ALC1200 on a P6T Asus Mainboard.
You can test the outputs at the speaker configuration : On every speaker you click you have to hear the test sound. If not, something is wrong with your configuration. Trial and error was the key for me - just keep trying to aggregate the outputs as long as you find the right working config to hear the test sound coming from the right speaker. In my case I gave this configuration the name Surround 5.1
4. Set SystemPreferences/audio output to soundflower 16 channel
5. Launch the Soundflowerbed Application and set Soundflower16ch device to your Surround 5.1 Speakers.
6. Set the Soundflower Channels 1 to 10 to "none" and assign 11 to 16 to the 5.1 channels : 11 goes to Surround 5.1(1), 12 goest to Surround 5.1(2) and so on.
7. Launch AULab from /Developer/Applications/Audio and configure as shown in the following screenshots:
Note : This is where the existing tutorial gets unusable because input and output always remains at the same setting : Soundflower16ch , and that's OK for me in my config.
8. In AULabs set Audio1, Audio2 and Audio3 to sound input Soundflower 1-2 by clicking the audio-tabs and moving the slider to AudioInputs1-2 - Maybe a picture explains more than I can do with words. Configure it just the way as seen on the following picture. There are several steps to do to reach that but I can't remember at the moment how I got to this config.Maybe too much beer - Feel free to ask questions at a later moment.
And don't be confused by the grey FR FL etc. entries on the right side of the picture - I just renamed those for my purpose of identifiing the outputs.
So please do anything to look like the above picture.
9. At last I went to SystemPreferences/Users/and added the generatedAULabs Config & Soundflowerbed to LoginStartup items.
This is not a perfect detailed instruction, but i wanted to give hints in time. Maybe later I will explain in detail what I have done. Excuse for the beer, and have fun !