I found how easy is to install Beryl and emerald on Feisty, I have this Feisty Fawn which started as Dapper, then upgraded to Edgy and now Upgraded to Feisty Fawn, I have never installed Beryl nor Compiz on this PC, an Intel Celeron with Intel Video Card embedded on the mother board. Ok, to install Beryl on Feisty all you have to do is: Go to System -> Preferences -> Desktop Effects,
and enable the Desktop Effects and the Desktops on a cube.
Later open a console, and type this:
sudo apt-get install beryl beryl-manager emerald-themes
After that run beryl by issuing the command
and that is all, it is running.
Enjoy the new Beryl on your Feisty!