Can a script change a layer's opacity without affecting history state?

I'm automating Photoshop and have implemented a simple feature that involves fading the top layer of the active document in and out, repeatedly by changing its opacity from a timer's tick event.

The key bit of code that I use to change a layer's opacity is:

ActiveDocument.ArtLayers(layer).Opacity = opacity

This works well except that it fills the history with opacity state changes.

Is there a way to avoid having the opacity change step recorded in the history or a way to remove the last step recorded?

Thanks.