Doing this by memory here... the mine entrance can be accessed when you go through the swamp into the area where the T'Rang are... if you go through the secret door, then talk to that T'Rang which tells ya to talk to Z'Ant, click on the purple buttons on the wall, and a panel will lift, which will give directions how the mine should be set up. Then go up the path, there should be a shack, some stuff on the wall which is where you change the directions of the "mine." Set it up that way and follow that through.
If I am not mistaken, you follow that around - and use the catapult thingie to get access. Then from there it's foggy. I can't recall if it's there, or if you have to go into the glass room and onto that elevator thingie. But it's in one of the upper rooms of the castle - because I remember after I got the idol and (well something happens), I peered through the window upstairs and could see bugs downstairs.
(Sorry at work, and been playing Wiz8 nearly non stop so everything's really fuzzy in my head... someone with more sense can probably tell ya more detail, or correct me, LOL)
