Google Tag Manager custom event listener not working

Question

I'm creating a event listener in the Google Tag manager, that should listen to any keypress. I followed this guide.

Here is my change listener:

<script>
  var eventType = "keydown"; 
  if (document.addEventListener) { 
    document.addEventListener(eventType, {{generic event handler}}, false); 
  } else if (document.attachEvent) { 
    document.attachEvent('on' + eventType, {{generic event handler}}); 
  }
</script>

I included the fields and tags as in the blog. Now I couldnt find the Document Path in the Tag setup. There is only the option to setup the fields one by one. Did anyone recently setup a Listener with the new UI and can tell me how to setup correctly?