Hop on the sewer grate and then over the wall into the moat. go to the Barge and get out (bell area) avoid the guard go up the stairs and go left to the exit from the moat area. Follow the Aquaduct about half-way to the next road. The NW side if the Ironforge Exchange is to your right.
This zone is laid out the exact same as a Qeynos tradeskill instance. You need to find 3 things which can be found in different spots each time you do the quest (how much variation is unknown):
the recipe which is a flittering paper sitting on a bench (reported near cookstoves and engraving tables) (-20, -6, 31)
alchemical temper (to contaminate mixture) see-through bottle is on top one of the shelves that hold the blue bottles (reported near forges)(-15, -6, -37)
use the temper to contaminate large keg (reported near chemistry tables)
Beware the Ironforge guards once inside the instance. There is one immediately on entry and a roaming Sergeant who may link with him, as well as two guards at every doorway throughout. These guards will all scale to your level or your level plus two.
There are also at least two Ironforge alchemists that spawn near the bottom of the stairs inside that lead to the crafting area itself. They will also attack with the guards, so you may have as many as 4-5 mobs attacking you at once. The alchemists will be your level.
There is a named mob in here who can see invis, Scribe Bogfizzle. She was one level higher solo and gave -100 Ironforge Exchange faction when killed. Also note that each of the doors is guarded by guards.