You'll need more dryhops if you want to mimic the aroma from Zombie Dust.
I'd do 4 oz of Citra in primary as the fermentation slows down (airlock bubbles every 15 sec or so). Rack off after no more than a week. Add 4 oz more to secondary/keg in a hop bag. Taste after 3-4 days and pull them out if there's any sign of "green", grassy, vegetal flavors.
It sounds like overkill, but that's the 3Floyds way.