<ScrollViewer x:Name="scrollViewerChannelBtns" Grid.Row="1" HorizontalAlignment="Left" VerticalAlignment="Center"
              Background="Transparent" VerticalScrollBarVisibility="Hidden" HorizontalScrollBarVisibility="Hidden"
              CanContentScroll="True" ScrollChanged="ScrollViewerChannelBtns_ScrollChanged">
    <StackPanel x:Name="channelBtns" Orientation="Vertical">
        <ItemsControl x:Name="channelBtnItems" ItemsSource="{Binding}">
            <ItemsControl.ItemTemplate>
                <DataTemplate>
                    <ToggleButton x:Name="tgbChannelName" Width="{Binding Path=ChannelNameBtnWidth}" Height="{Binding Path=ChannelNameBtnHeight}" HorizontalAlignment="Left" VerticalAlignment="Center" IsChecked="{Binding Path=IsChecked, Mode=TwoWay}" Content="{Binding Path=ChannelName}" Tag="{Binding Path=Index}"/>
                </DataTemplate>
            </ItemsControl.ItemTemplate>
        </ItemsControl>
    </StackPanel>
</ScrollViewer>

//The button click event handled
private void BtnScrollDownClicked(object sender, RoutedEventArgs e)
{                        scrollViewerChannelBtns.ScrollToVerticalOffset(scrollViewerChannelBtns.VerticalOffset + 50);
}
private void BtnScrollUpClicked(object sender, RoutedEventArgs e)
{                        scrollViewerChannelBtns.ScrollToVerticalOffset(scrollViewerChannelBtns.VerticalOffset - 50);
}

xmlns:sys="clr-namespace:System;assembly=mscorlib"

<Grid>
    <ScrollViewer x:Name="scrollViewerChannelBtns" HorizontalAlignment="Center" Height="100" CanContentScroll="False" VerticalAlignment="Center"
          Background="Transparent" VerticalScrollBarVisibility="Auto">

        <StackPanel x:Name="channelBtns" Orientation="Vertical">
            <ItemsControl x:Name="channelBtnItems">
                <ItemsControl.ItemTemplate>
                    <DataTemplate>
                        <ToggleButton x:Name="tgbChannelName" Width="40" Height="20" HorizontalAlignment="Left" VerticalAlignment="Center" IsChecked="{x:Null}" Content="Test" />
                    </DataTemplate>
                </ItemsControl.ItemTemplate>

                <sys:String>Item 1</sys:String>
                <sys:String>Item 2</sys:String>
                <sys:String>Item 3</sys:String>
                <sys:String>Item 4</sys:String>
                <sys:String>Item 5</sys:String>
                <sys:String>Item 6</sys:String>
                <sys:String>Item 7</sys:String>
                <sys:String>Item 8</sys:String>
                <sys:String>Item 9</sys:String>
                <sys:String>Item 10</sys:String>
            </ItemsControl>
        </StackPanel>
    </ScrollViewer>

    <Button Name="Up" Width="50" Height="30" VerticalAlignment="Top" Margin="110,0,0,0" Content="Up" Click="Up_Click" />

    <Button Name="Down" Width="50" Height="30" VerticalAlignment="Top" Margin="210,0,0,0" Content="Down" Click="Down_Click" />
</Grid>

private void Up_Click(object sender, RoutedEventArgs e)
{
    scrollViewerChannelBtns.ScrollToVerticalOffset(scrollViewerChannelBtns.VerticalOffset - 50);
}

private void Down_Click(object sender, RoutedEventArgs e)
{
    scrollViewerChannelBtns.ScrollToVerticalOffset(scrollViewerChannelBtns.VerticalOffset + 50);
}

ScrollViewer.UpdateLayout();
  ScrollViewer.ScrollToVerticalOffset(outPoint.Y);