The quest mechanics work but you don't get credit once you're flight is over and you are not transformed to the fire wisp. Ref.#4456

hash: b3bdcc6

DDuarte:
... scripting the dummy aura of http://www.wowhead.com/spell=36587 seems a good place to start.

Subv:
You could script spell 36587 to cast 36573 on its dummy aura, there should be an areatrigger on the quest complete location.

Svannon:
Vision Guide Kill Credit Trigger (21321) and the spells subv2112 pointed out.