How to Embed Arbitrary Content in a WPF Control

<ResourceDictionary
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:MyControls">

    <Style TargetType="{x:Type local:HeaderFooterControl}">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type local:HeaderFooterControl}">
                    <StackPanel Orientation="Vertical">
                        <ContentPresenter ContentSource="Header" />
                        <ContentPresenter />
                        <ContentPresenter ContentSource="Footer" />
                    </StackPanel>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</ResourceDictionary>