How to control 3d printer printing in metal?
Pronterface would control the printer, but you would need a slicer that could give you g-code that works with said metal printer. Being it would be using metal, most of those are powder based, using a laser to sinter. The slicers for FDM based machines would not create the correct g-code for the application. I know there has been some effort around powder based printers (both metal and plastic) but I do not know of any software that has resulted from these efforts.

This wiki index for powder printers may be of some help to find out what software they are working on, most likely a custom solution.
http://reprap.org/wiki/Powder