Hi!
To activate the brewfest boss in BRD enter with someone that has server transfered recently and is at level 80 (We also had some low level alts with us but do not know if this effects the bug or not) when you enter you will be asked "Do you wish to join a group for Coren Direbrew?" click accept and the brewfest mobs will be to your right simply click the brewfest controls and you will be taken to the bar.
The quest is no longer needed and you can just talk to him and start off the event he now drops 2 trinkets per attempt and each person will recieve a Keg-Shaped Treasure Chest which contains a small ammount of gold 2 frosts and a chance at any of the vanity items that used to drop from the boss.
Here is an armory screenshot showing one of the characters earning the achievement and gaining loot in may and also being under the level required to que for the event in the first place.
Uploaded with ImageShack.us