i was hoping you didnt notice
i have been trying to extract the signature files before, but without results unfortuanately
i did a search on the avast directory and found several VPU files in the setup directory, one of those is about 34MB (at this moment) which is the same as the executable size....
you could do it the hard way and have a tool monitor the files that are in the avast directory then show the files that changed after you do an update (from which you know for certain that its the definitions update).....
then you can copy those files to the share for the bart cd users
i check the vpu file and the header starts with ASWsetupFPkgFile (just for extra info)