How can I change sprite in animation clip by code?

hai guys!
I want to change sprite in animation clip.The 2d animation clip is created by editor,and I want to change sprite by script.
I know this funtion AnimationClip.SetCurve(),but keyframe is only support float type.so how
can i do that?
Thanks for your time!

(I have an asset on the store for this - Unity Asset Store - The Best Assets for Game Making)

This thread may have a solution for you: http://forum.unity3d.com/threads/212615-Lack-of-scripting-functionality-for-creating-2D-animation-clips-by-code