There is a door over by one of the two Alchemist, I forget the name, but the one with less of an attitude.
It does have some apparently somewhat difficult monsters, but I was cheating my ass off, and didn't notice. Just a heads up.
The door to the study is along the cliff face opposite of the alchemist, if you run along that, you should find it.
I had a fair amount of running over the island to find it myself.
Good luck.
Thanks for the info. I've managed to discover the entrance after some running all over the place.
Now I'm stuck in finding the name of the (can't remember the name) in order to kill evil mage. I'm in a study with a mute goblin and I've search everywhere with success for the name. Any pointer from you?