Where to find Constraint IPOs?

I’m creating a script here to fill a time sink in using Blender3D for game creation in terms of animations. The problem is that game animations are stored in Action objects ( as this is easy to export and fast to work with ). Now often you end up with duplicates or one action but a slight modification ( example: walk, walk 45° left, walk 90° left, walk 45° right, walk 90° right ). Since most of the channel IPOs are the same and only a few changing ( using a lot constraints ) it would be very helpful to copy IPO curved from for example the base walk animation over to all other similar animations. Blender itself lacks an easy way for this ( you can do it, but it’s cumbersome ).

Now I made the script which can copy the Pose IPOs from one action to another ( with properly clearing the old IPOs and full copy the keys ). The only problem are the constraints. They have an IPO curve too but I can’t find out how to get access to them from within python. What object are they attached to? Constraint? PoseBone? Something else? The API documentation did not give me a hint yet.