Well, maybe it would be BT-LR, but either way, it seems reporting services gives you 2 ways to align your text.
LR-TB, and TB-RL (Left to right, top to bottom, and top to bottom, right to left).
The problem with this is of course, that no one writes (english) top to bottom, right to left. When you write text in a vertical fashion, it is always bottom to top, left to right.
In other words, you tilt your head to the left to read it.
I found this post on the topic where it sounds like someone might have come up with a creative way to rotate the TB-RL text 180 degress.
I haven’t tried, it, but it seems like the only hope out there.