Winlist NG works like this:
Load the module, then open the settings panel and go to the input tab.
Open the 'key bindings' config screen and select the Alt + Tab combi, then on the right side select NG Winlist/ Show next window.
Then use Alt + Shift + Tab for 'show previouw window' and click apply
Now when you switch windows with alt + tab or alt + shift + tab the winlist ng will popup.