ok if you go this way prepare yourself for 3 achievement's the ones your going to hope fully get going this route are:
Serious Academic
Back to school
Chosen
the co-ords for the hole is X:378 Y:693 my highest wits found it she was wits lvl 23!. I started from the "Temple of Zorl-Stissa" head east a little to X:249 Y:695 and used Phoenix Dive to get to the hole im sure you can use what ever else such as cloak and dagger, tactical retreat what ever method just get there and use a tele pyramd to drg the rest of you team there and done...once in the hole Quick save because as soon as you touch the door you get the "Chosen" achievement dialogue options ...I need to persuade two of my team again was no issue at my persuasion lvl of 5 once all agreed if possible enter the door and pop goes the other achievement's!! DING DING DING