While I don't know if he'll help you very much, there's always been that one roaming NPC that's been really thief friendly. He's got a little more clout now.

If he doesn't, I suggest you try finding the passage near the place that every thief tries to avoid getting sent to.

Nikpack

Climbing List:http://www.elanthipedia.com/wiki/Climbing_skill
Swimming List:http://www.elanthipedia.com/wiki/Swimming_skill

And while I am evil, I try to avoid being just plain mean.
-Z