WPF Slider Draggable Only

I have a strange requirement to make a slider in a WPF application dragable only, meaning that clicking on the slider track should not move the slider, it should only move when the user clicks and drags the thumb. Is there a way to accomplish this in WPF? I saw a post suggesting you derive a custom control from Slider, but there are only 4 virtual methods, and non seem to be helpful.

This is the slider definition I have now.

<Slider Name="radialSlider" 
        Width="150"  
        VerticalAlignment="Center" 
        TickFrequency=".005" 
        Minimum="-.25" 
        Maximum=".25" 
        IsSnapToTickEnabled="True" 
        ValueChanged="radialSlider_ValueChanged" 
        Thumb.DragCompleted="radialSlider_DragCompleted"  
        Grid.Column="1">
</Slider>