Entrance to the zone is in Nektulos Forest at ( 883, 7, -470 ) /waypoint 882.72, 6.97, -470.17.
You no longer have to do the Access quest to enter this zone.
Cauldron Hollow Revamp (Live Update #45) Edit
Cauldron Hollow was revamped with LU45. It is now a heroic zone requiring a single group of players 30-36. There are 3 sub-bosses to be defeated, Bumwuk the Opressor, Haunted Nightmare, and The Troll Plunderer.
The final boss, Descendant of the Torig, is an 35^^^ heroic with two no-arrow adds. Note: He hits extremely hard so make sure your healer realizes this before going in. No surprises. Visit the wiki page for Descendant of the Torig linked in the paragraph above.
There is a key (A Witch's Key) which drops from random mobs throughout Nektulos Forest that gives one-time access to a special instance of Cauldron Hollow called Cauldron Hollow: The Witches' Cove. 30