WPF CheckBox style with the TextWrapping

I need to apply a TextWrapping in the WPF CheckBox.

Please look at this two samples:

<CheckBox>  
  <TextBlock TextWrapping="Wrap"  
             Text="_This is a long piece of text attached to a checkbox."/>  
</CheckBox>

<CheckBox>  
  <AccessText TextWrapping="Wrap"  
              Text="_This is a long piece of text attached to a checkbox."/>  
</CheckBox>

If I use a TextBlock in the Content of the CheckBox, the check element (vertical alignment is top) and the text displays properly, but not the accelerator.

If I use an AccessText in the Content of the CheckBox, the check element displays wrong (vertical alignment is center).

How can I change the Style of the elements to display this CheckBox correct?