I downloaded AutoScale from http://blog.maartenballiauw.be/post/2011/03/21/Windows-Azure-and-scaling-how-(NET).aspx and followed the instructions there. I added it as reference to my existing azure project. But I am not sure what exactly I should pass as the user defined parameters for the 6 parameters required for auto scale.
I want to only change the instance count of my worker role depending on the number of documents to be processed.