Make your image layer a normal layer id a background layer
dupe the image layer for as many images as you want.
Use Canvas size to set the Paper size you want
Use Images size uncheck resample set the Print Resolution you want to print at.
Use Free Transform to distribute the image layer over the canvas.
You can also use a script to layout images for you. http://www.mouseprints.net/old/dpr/PasteImageRoll.html