Andy,
You can do this using a Property Node to change the Front Panel>>Origin property. I have attached an image of a simple method. The Current VIs path is wired to the Open VI Reference, then a property node set to Front Panel>>Origin, and finally a Close Reference. The Front Panel.Origin property is a cluster of I32s containing the Horizontal and Vertical position.
Regards,
Aaron
LabVIEW Champion, CLA, CPI