Firstly install Ubuntu 6.06 (Dapper Drake), it makes all sorts of fancy and advanced things easy to do :)
Assuming that you are using Enlightenment DR17 already (isn't everyone?) (get-e.org) we need to install the composite extension and some handy tools.
apt-get install libxcomposite xcompmgr transset
Once these are installed we need to edit /etc/X11/xorg.conf. Add the following section to the end of the file
Section "Extensions" Option "Composite" "Enable" EndSection
After that you need to restart your Xserver (Ctrl-Alt-Backspace (with no open work) should do the trick).
It is advisable to unload the dropshadow module at this point, as it draws to the desktop and can create some really peculiar results when it shines through the windows.
now start the composite manager - xcompmgr -fF is my preference - it turns on window fade in / out and also fades from one transparency level to another.
Voilla! you can now set the opacity of individual windows using the "transset" command - give it a shot. Clearly you should make a .eap for the xcompmgr command and place it in ~/.e/e/applications/startup/
-- HandyAndE