I think you just need to set charting.legend.placement to "bottom"
In Sideview Utils XML,
<module name="ValueSetter">
<param name="arg.charting.legend.placement">bottom</param>
In Advanced XML:
<module name="HiddenChartFormatter">
<param name="charting.legend.placement">bottom</param>
And in simple XML, I believe you would add this to your ``
<option name="name">charting.legend.placement</option>
You may need to elaborate what you've already tried, what you specifically need, and how your attempts are failing to do what you need.