How do you control the duration or speedratio parameters in a storyboard via a slider?

Question

I created the following storyboad to continually rotate an image:

     <Storyboard x:Key="Rotate">
        <DoubleAnimation
            Storyboard.TargetName="arrowRotate"
            Storyboard.TargetProperty="Angle"
            From="0.0" To="360.0" Duration="0:0:0.25" SpeedRatio="1"
            AutoReverse="False"
            RepeatBehavior="Forever"/>
    </Storyboard>

How do I wire a slider to control the duration or SpeedRatio parameters in the storyboard?

Thank in advance for your help.

-Eddard-