This code allows you to place the legend inside the plot area.
<cfx:Chart Grid.Column="0" Grid.Row="0" Grid.ColumnSpan="2" Grid.RowSpan="2" Name="ctlChart1">
<cfx:Chart.PlotArea>
<cfx:PlotAreaAttributes ClipToBounds="false"/>
</cfx:Chart.PlotArea>
<cfx:Chart.LegendBox>
<cfx:LegendBox Visibility="Visible" cfx:Chart.TargetPanel="Inside" DockPanel.Dock="Top" HorizontalAlignment="Right" Margin="4" Background="Yellow">
</cfx:LegendBox>
</cfx:Chart.LegendBox>
</cfx:Chart>