Edit Mecanim curves through scripts

When I import an fbx character, select it in the Projects window, and set the inspector to the Animations tab, there's several options at the bottom : Mask, Curves, Events and Motion. Are there any runtime or Editor functions that will allow me to add and edit contents in the Curves section?

I'm trying to make an editor script that programatically adds curves, but I can't find out how to get access to them.