Heya;
I remember this one - I found it difficult myself. Though not nearly as hard as the lift in the Arena...
I managed it by placing the slate in a position where the bahro appears right when I'm on the lift (Common sensically...) I can't remeber which symbol I used - I think it may have been that one... If you go through all the journals and use the different symbols you've seen around the place, you should be able to find the one that makes the bahro stick around long enough to reach the top - as soon as you're in the upper floor, start running against the wall so as soon as you're high enough, you move off it (I play it in the 'free-roam' style like Uru and RealMyst are played. This may help.)
Any snake symbol may work too - as they seem to cower for a while...
Hope this helps

YES! I am still alive.