I hope it makes you cry with happyness.
Hey I thought of another way to fix your problem, so on your view have it implement some interface, like IFocusable or something, where IFocusable looks like this
public interface IFocusable
Then in your ViewModel you can grab the View using that interface using the ViewAwareStatusService something like this:
IFocusable focusable = this.ViewAwareStatusService.View as IFocusable;
focusable.Focus(name of element you want to focus);
Then in the View that implements IFocusable, when the Focus() method is called, you will need to find the element requested (this.FindName or some VisualTree thing) and Focus it.