Blender exported to Unity, bone rotation and parenting.

I created a model and exported the *.fbx to unity. Now when manipulating the bone with rotation, it faces to the opposite direction. I tried to do it as described here

But when I set the bone as Parent to the bone which faces opposite in the object editor, it fucks up the position of the bone, and I see the mesh doubled in unity. Beyond that, it does nothing when I try to manipulate the bone which faces opposite.

I tried to add a Bone Constraint, which works fine in Blender, but exported as *.fbx to unity, it doesn't work there. I guess Bone Constraints aren't exported.

So, how do I need to configure the bones so I can manipulate them in unity without them to face in the opposite direction?

I'm using Blender 2.56

Make sure your bone axis are set up correct. Hmm, about the fuck-up thing when you set bones as parent, could you post a picture of it? I'm not sure I understand it.

Also, are you using IK's in blender? I tried importing a rig with IK's from blender and my character gone crazy for some reason, even though the IK were set up properly and IK settings in unity was checked.