Please be aware of that it's currently a prototype and won't work properly in all cases, it can even break the alt+tab behaviour completely therefore you install this on your own risk.
This is a modified version of the original Gala Alternate Alt-Tab Plugin by Tom Beckmann.
Instead of showing icons, this version shows a window overview like preview of the current workspace.
$ mkdir build && cd build/
$ cmake .. -DCMAKE_INSTALL_PREFIX=/usr
$ make
$ make install