Python-Exression driven IPOs for Armature - How do I access RotY?

Hi, I’m working on rigging my old F1 contest entry, and to get the “feathers” to work right, I need to do the following:

I need to “drive” the rotation of one bone with another bone - in the same armature. I tried doing this without python expressions, but it won’t let me, saying “Cannot assign a Driver to own Object”. So, I looked around, and found you should be able to do this with python expressions.

Something along the lines of


should work, but I don’t know exactly what to enter. Could someone give me an example of the proper expression, please?

I may have found a partial solution.
The code…

import Blender
loc = Blender.Ipo.Get('ActIpo')[Blender.Ipo.OB_LOCX]
print loc[Blender.Get("curframe")]

…should get me the value an IPO channel at the current frame. Obviously, I need to change OB_LOCX to whatever QuatY would be (OB_QUATY, maybe?), but that’s not the main problem with this method.

My main complaint is that the controller bone has to have an IPO for this to work. Ideally, I’d like to be able to rotate the controller bone, and have the IPO-driven bone/bones move with it in realtime. I should be able to do this if I get the current rotation of the controller bone… something like Blender.Pose.Get[OB_QUATY], but once again, I don’t know the exact code. Can anyone help me, please?