binding to width property in code behind

I have a situation where I need to create View box with one button. The xaml for this is as below: Please observe Width property of viewbox. The Width should be increased/decreased according to a slider bar(moving to right increases it, to left decreases it). As listed below I know how to do it in xaml and it works fine. But my requirement is to be able to create viewbox in code behind and assign it the properties.

 <WrapPanel x:Name="_wrpImageButtons" Grid.IsSharedSizeScope="True"
           ScrollViewer.CanContentScroll="True" d:LayoutOverrides="Height" 
           Margin="5">
    <Viewbox x:Name="_ScaleButton" 
             Width="{Binding Value, ElementName=ZoomSlider}" Stretch="Fill">
         <CustomButton:_uscVCARSImagesButton x:Name="_btnImage1"/>
    </Viewbox>
 </WrapPanel>

Thanks.