Start with a control in your template. Get a reference to that control and cast it to VIRefNum. Then call the 'Make Strict Reference' method using a VI reference to the desired VI. Finally, get the Terminal reference of the VIRefNum and invoke the method 'Change to Constant'. The constant winds up in a different location, if you are OCD like I am then read the position of the control terminal before and write that position to the constant after.
It is pretty common to have more scripting versatility with a control or indicator than the corresponding constant.