As ddanbe told you can not do with disigner.
You can do one more Thing that is:
Add PictureBox (Properties: Transparent)
Now add image to that Properties. (mousehover)
Now add another image. (mouseleave)
add third image (mouse click)
2.) Add the Codes as you add for the button.
I know This is not your point of view but this will atleast give you Irregular shape button look.