como eu acessaria esse recurso XAML do WPF programaticamente?

<Grid.Resources>
<Style x:Key="lineDataPointStyle" TargetType="chartingToolkit:LineDataPoint">
                        <Setter Property="Background" Value="DarkGreen"/>
                        <Setter Property="IsTabStop" Value="False"/>
                        <Setter Property="Template" Value="{x:Null}"/>
                    </Style>
</Grid.Resources>

e aqui está o código de onde eu quero acessá-lo. Note que eu preciso criar programaticamente as linhas:

 // New Assoicated Graph Series
                var lineSeries = new LineSeries();
                lineSeries.ItemsSource = newSeriesCollection;
                lineSeries.IndependentValuePath = "Second";
                lineSeries.DependentValuePath = "Kb";
                lineSeries.Title = kvp.Key;
                lineSeries.DataPointStyle = (Style) this.Resources["lineDataPointStyle"];  // ** DOES NOT WORK