final TextPainter flatCellPainter = new TextPainter();
final ButtonCellPainter bcp = new ButtonCellPainter(new BeveledBorderDecorator(flatCellPainter), new BeveledBorderDecorator(flatCellPainter, false));
config.registerConfigAttribute(CELL_PAINTER, bcp, NORMAL, MY_BUTTON_LABEL);
bcp.addClickListener(new IMouseAction() {

    @Override
    public void run(final NatTable natTable, final MouseEvent event) {
        // do stuff
    }
});