Handling Key press & release events in MVVM

I am developing a wpf application using MVVM pattern. I need to separately handle Key press & release events, (e.g. in media players fwd/rev happen till user keeps key pressed & stops when he releases). After searching a lot, still I couldn't find any way to do it. Can anybody please help.

Thanks for your suggestions. I found a way to do this by using interactivity triggers & dependency property. Following is the dependency property for Command.

public class EventToCommand : TriggerAction<DependencyObject>
{
    public ICommand Command
    {
        get { return (ICommand)GetValue(CommandProperty); }
        set { SetValue(CommandProperty, value); }
    }

    // Using a DependencyProperty as the backing store for Command.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty CommandProperty =
        DependencyProperty.Register("Command", typeof(ICommand), typeof(EventToCommand), new PropertyMetadata(null));

    protected override void Invoke(object parameter)
    {
        if (Command != null
            && Command.CanExecute(parameter))
        {
            Command.Execute(parameter);
        }
    }
}

Then just use it in the xaml as below:

    <i:Interaction.Triggers>
    <i:EventTrigger EventName="KeyUp">
        <ap:EventToCommand Command="{Binding KeyReleaseCommand}"></ap:EventToCommand>
    </i:EventTrigger>
    <i:EventTrigger EventName="KeyDown">
        <ap:EventToCommand Command="{Binding KeyDownCommand}"></ap:EventToCommand>
    </i:EventTrigger>
</i:Interaction.Triggers>

Where the KeyReleaseCommand & KeyDownCommand are RelayCommand in your ViewModel.

    public MainViewModel()
    {
        KeyDownCommand = new RelayCommand<KeyEventArgs>(OnKeyDown, null);
        KeyReleaseCommand = new RelayCommand<KeyEventArgs>(OnKeyRelease, null);
    }

    private void OnKeyRelease(KeyEventArgs args)
    {
        if (args.KeyboardDevice.Modifiers == ModifierKeys.Alt)
        {
            if (args.SystemKey == Key.Left)
            {
                Trace.WriteLine("ALT+LEFT Released");
            }
        }
    }

    public void OnKeyDown(KeyEventArgs args)
    {
        if (args.IsRepeat)
            return;

        if (args.KeyboardDevice.Modifiers == ModifierKeys.Alt)
        {
            if(args.SystemKey == Key.Left)
            {
                Trace.WriteLine("ALT+LEFT");
            }
        }
    }