Can I get an animation to Auto Key values set in custom inspector?

I am adding weapon effects locators to sprites, and wish to animate them (using the Animation Window).

I have written a custom editor class so that I can manipulate the positions with handles in the scene view, which works fine... except for when I do so, it does not automatically key the positions in animation mode (but it is fine if I manipulate the values in the inspector director).

Is there a simple way of enabling this - like an animation equivalent of SetDirty?

Thanks