Getting Started:You probably want to form the group before you head to the instance, as most people already in the zone seem to have already used their summon. As with other such daily summons, the liars seem to come out of their hiding places, so if you want to guarantee that everyone actually has their summon, I'd recommend grouping with friends.
Even for a well geared group, having a second tanking type makes the encounter so much easier. A real tank would be best, but even a leather or mail wearing DPS could fake-tank one of the mobs and make the fight go smoothly, and save your healer a good bit of stress.
You don't have to do anything before going to the instance. Summon, zone in, the guy by the inner door offers the daily quest and the bag. Open the bag, and have all melee but your fake-tank use the purple potion (Perfume Neutralizer). Have your last member drink the green potion (Cologne Neutralizer.) Healer and ranged can drink either, they'll just have to move out of the other color puddles on the ground.
Elaborating more on this: The Perfume Neutralizer (purple) will make you not take most damage from the boss with the purple bubble and the purple puddles on the ground. The Cologne Neutralizer does the same for the green equivalents.
Once you turn in the quest, there's some chat from the head apothecary, and then the fight begins. Be careful not to turn in the quest until your group is all ready.
The purple mob, Apothecary Hummel (marked Skull in the picture), will become active first. His bubble will do significant damage to anyone within a few yards of him, unless they are using the purple potion. The tank needs to try and turn him so that his spray will not hit the ranged. Tank him where he stands, and DPS him down.
After Hummel is dead, your main group should then swap to the third baddy, Apothecary Fyre (marked triangle). After the quest is turned in, he'll run to where the triangle is very artistically drawn on the SS. It takes a few seconds, but once he activates, he'll be running haywire everywhere and generally pissing off your tank and melee, but kill him as best you can, while avoiding the pink and green puddles he leaves on the ground. He does some minor melee damage, but his main attacks are the puddles he throws. As long as your group can move out of the ones that are doing damage to them, he's fairly easy.
During this, the second mob, Apothecary Baxter (X in the SS), will become active. He'll have run over to the X on the picture, and should be 'tanked' where he stands by your green dps. Your fake-tank will want to keep Baxter facing away and at distance from the main group, as his aura and spray will do lots of damage to anyone that's not immune to it. Once the main group has killed Fyre, they can come over and help kill Baxter. The melee may want to swap to the green potion as they're running in.
Once they're all dead, head back over to loot the shinies. Good luck on the mount =)
For a very well geared group, it is possible to power through the encounter without a second tank. It's hard on the tank and healer though, and you shouldn't have too much trouble finding a fake-tank. My dps geared, specced, and presenced DK took care of Baxter with no problem. It really depends on your gear level and the amount of melee/ranged dps you have as to if tanking them separately is vital or not. Use your best judgement =)
There are little adds that run around during the encounter, but their damage is unnoticeable.
You'll probably need to refresh your potion between each kill, but you may have to cancel the buff first in order to get the timer to restart. It's been acting odd, and hasn't been fixed as far as I'm aware.
I wouldn't suggest doing this with less than 3, as at least one healer, and dps are probably needed to kill the group before you healer starts going OOM. You could fake tank the entire thing, but a real tank makes your life easier. And you will need a healer. Because healer's are sexy.
Got questions? Ask! I'll do my best to reply =)