Protected Overridable Sub PrepareContainerForItemOverride ( _
    element As DependencyObject, _
    item As Object _
)

Dim element As DependencyObject
Dim item As Object

Me.PrepareContainerForItemOverride(element, _
    item)

protected virtual void PrepareContainerForItemOverride(
    DependencyObject element,
    Object item
)

protected:
virtual void PrepareContainerForItemOverride(
    DependencyObject^ element, 
    Object^ item
)

protected function PrepareContainerForItemOverride(
    element : DependencyObject, 
    item : Object
)

You cannot use methods in XAML.