How to Highlight Portion of Chart?

Oct 8, 2011 at 11:40 PM

I have a chart:

         <ddd:ChartPlotter x:Name="volume"   LegendVisibility="Hidden" NewLegendVisible="False" Grid.Row="3" >
            <ddd:WidthSpring SourcePanel="{Binding LeftPanel, ElementName=ma}"/>
            <ddd:BarChart Fill="DarkGoldenrod"  Stroke="Brown" DataSource="{Binding VolumeDS}" >
                <ddd:NumericAxis LabelProvider="{StaticResource tickToDate}"/>
The X axis is days. it could be any number of days total, for example, 180 days or 60 days. 
I want the last 5 days days displayed on the right of the chart to be highlighted with a different. I want the chart to display over
the highlighted color.
How do I accomplish this, either in Xaml or C#?