Avast 8 into Windows 8.1 Preview?

I am trying to install the latest version of Avast 8 into the Microsoft Windows 8.1 Preview, but I get a message saying it is incompatible and cannot be installed. They offer a ‘solution’ response which is to contact Avast!
So how do I install it? I have downloaded the latest available version from your website but I gather from the Microsoft response that an additional file is needed to make it install properly.

maybe this help

http://forum.avast.com/index.php?topic=128284.0

Or this page?
http://www.avast.com/en-us/faq.php?article=AVKB97#artTitle