I believe some people have set it up. It is a matter of converting the audio from the AJA breakout box for your 5.1 receiver (usually analog). You have the AES EBU outputs and the embedded SDI output.
If you use the AES, you can use a D->A converter. You can also de-embed the SDI audio.
Blackmagic HDLINK can de-embed and convert analog in a single box (amongst other things)
http://www.blackmagic-design.com/products/hdlink/Hope that helps. It is possible. How you decide to achieve it will depend on what gear you already have.
cheers
Jason