How can I use an ElementName binding within a ControlTemplate?

I have multiple TextBlocks which reference different elements in my application. My code works fine when used directly in the page. However, I want to create a ControlTemplate and a ContentControl to reduce the duplication of code.

How can I pass a reference to an ElementName into the ControlTemplate from the ContentControl using TemplateBinding? The following code throws this error:

"Cannot convert the value in attribute 'ElementName' to object of type 'System.String'. Object of type 'System.Windows.TemplateBindingExpression' cannot be converted to type 'System.String'. "

In addition to the Tag attribute, I have tried ContentStringFormat which also did not work.

What is the correct method to get this to work using templates?

Thanks in advance for your help,

--- Shawn

Here is the code sample:

<Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:sys="clr-namespace:System;assembly=mscorlib" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" >
    <Page.Resources>
        <ControlTemplate x:Key="MyTemplate" TargetType="{x:Type ContentControl}">
            <TextBlock Margin="{Binding ElementName={TemplateBinding Tag}, Path=Margin}" Text="{TemplateBinding Content}" TextAlignment="{Binding ElementName={TemplateBinding Tag}, Path=TextAlignment}" Width="{Binding ElementName={TemplateBinding Tag}, Path=Width}" />
        </ControlTemplate>
    </Page.Resources>
    <StackPanel>
        <TextBlock x:Name="AnotherElement" Margin="10" Text="Main TextBlock" TextAlignment="Center" Width="100" />
        <TextBlock x:Name="AnotherElement2" Margin="20" Text="Second TextBlock" TextAlignment="Left" Width="250" />
        <TextBlock Margin="{Binding ElementName=AnotherElement, Path=Margin}" Text="Here is my TextBlock!" TextAlignment="{Binding ElementName=AnotherElement, Path=TextAli