Silverlight Databinding - Binding a ValueConverter to a property on a view-model

<UserControl.Resources>
    <local:ViewModel x:Name="viewModel" />
    <local:LoadChildrenValueConverter x:Name="valueConverter" />
</UserControl.Resources>

<UserControl.DataContext>
    <Binding Source="{StaticResource viewModel}" />
</UserControl.DataContext>

<Grid x:Name="LayoutRoot" Background="White">
    <control:TreeView ItemsSource="{Binding Root}">
        <control:TreeView.ItemTemplate>
            <control:HierarchicalDataTemplate ItemsSource="{Binding Converter={StaticResource valueConverter}}">
                <TextBlock Text="{Binding}" />
            </control:HierarchicalDataTemplate>
        </control:TreeView.ItemTemplate>
    </control:TreeView>
</Grid>

<control:HierarchicalDataTemplate ItemsSource="{???}"

<control:HierarchicalDataTemplate ItemsSource="{???}"

public class ViewModel
{
    public ObservableCollection Root { get; set: }

    public ObservableCollection Children
    {
        get { /* return children items */ }
    }
}

<control:HierarchicalDataTemplate ItemsSource="{Binding Children}">

public class ViewModel : IValueConverter
{
    public static readonly IValueConverter ChildrenConverter
        = new LoadChildrenValueConverter();
}

<control:HierarchicalDataTemplate
    ItemsSource="{Binding Converter={x:Static local:ViewModel.ChildrenConverter}}">

public class ViewModel : IValueConverter
{
    // move your Convert and ConvertBack methods into here
}

<control:HierarchicalDataTemplate
    ItemsSource="{Binding Converter={StaticResource ViewModel}}">