I use PSEv.8
Print from the Editor
Crop your picture to 2x3"
Go to File>print. In the dialog:
#3 Paper size>4x6" and 4x6" borderless are listed
#4 Use individual print
#5 Print size is an option available to you. If you crop before sending it to the printer, you will have absolute control. Note the "crop to fit" box.