Absinthe was re-legalized for distillation late last year (Source
There are three main herbs that make up Absinthe: wormwood, green anise, and florence fennel (although there are various other recipes for the stuff, I think this would be the closest to the original).
You can try making a tea of fennel and anise. Star anise would probably work just as well is regular anise isn't available or more expensive by comparison. By boiling those two herbs in water you can make them release their aroma into the water. Since you're probably not gonna drink it (it would be rather bitter) you can let it steep for a while to get very aromatic; you can always dillute it later if it's too strong by adding more water. Strain out the plant material and then let the tea cool down; a few hours in the fridge should get it to a "hookah ready" temperature. Be sure to stir it vigourously after though because sitting in your fridge for that long would probably cause any particulate matter that was floating around to settle to the bottom of the container.
Adding a shot or two of either Absinthe or even Jägermeister or Sambuca (they all have that anise flavor) will probably make it further stand out.
Can't hurt to experiment.