I'd post some pics but my brother is using it at his place.
The idea is so simple, I'm surprised an attachment like this isn't commercially available.
EDIT:
I guess there are commercially available SSQA mixers:
Skid Steer Concrete Mixer Attachment
www.spartanequipment.com
And
Digga's range of Cement Mixers can mix anything from cement to fertilizer & fits quickly and easily to your Digga Auger Drive (Sold Separately). Shop today!
www.diamondtoolstore.com
Quite pricey though.
I picked up the stand mixer at a yard sale for $50. It had a bad electric motor that I replaced with a $150 hydraulic motor. I had the blank SSQA plate laying around so the whole rig cost $200.