How do I set up a workflow to autoemail the shipmentconfirmation report when the shipment has been confirmed?

I have been trying to set this up and getting close but failing to find how to do this correctly.  What I want is for the same process that happens when I press the email shipment action button manually to happen when the shipment is confirmed but I can’t work out how to achieve this.  Is this something I need to do in the workflow or does it need some customization code or am I looking in the wrong place completely? 

I managed to set up a business event which sends the email when the status reaches status confirmed but it doesn’t allow me to attach the shipment confirmation report to it so I don’t think that is the right way to go about it.

Thanks,

Phil