I have found the instrucions, they are located in
avast4workstation-1.3.0/share/doc/avast4workstation-1.3.0/
localhost avast4workstation-1.3.0 # ls
avast.pot EULA FAQ helpfiles INSTALL libs LICENSE README
Installing from tarball
=======================
No installation is required, files in the bin/ can be run directly after
unpacking the .tar.gz archive. If you would like to integrate avast! into
your KDE or GNOME desktop, run
./lib/avast4workstation/share/avast/desktop/install-desktop-entries.sh install
from the place where you unpacked the archive. Run
./lib/avast4workstation/share/avast/desktop/install-desktop-entries.sh uninstall
to uninstall previously installed menu entries.
Please see the README file and man pages for more information how to use
the program.