How can I simulate Photoshop’s History brush when using Elements?

1. Make a new layer at the top of your layers stack (use the New Layer button at the bottom of the Layers palette, or choose Layer > New > Layer).
2. Press Ctrl-Alt-Shift E to make a merged copy of your docuement on that new layer.
3. Turn off visiblity for that merged layer as you continue to edit the layers below.
4. When you want to add back part of the older version, turn visibility back on and use either the eraser or any of the various masking tricks to reveal that “history” state wherever you need it.