Dependency injection / IoC in Workflow Foundation 4

Is it possible to use DI in your workflow activities? and if yes, how?

For example if you have an activity like

public sealed class MyActivity : CodeActivity
{
    public MyClass Dependency { get; set; }

    protected override void Execute(CodeActivityContext context)
    {
        Dependency.DoSomething();
    }
}

how can i set Dependency?

(I'm using Spring.Net)