Do you want crop marks at set points across the image? If so, just draw a line in Photoshop, there are rulers along the edge of the screen so you can set them where you want them (view > rulers if you don't see any). Expand the canvas slightly along one edge if you don't want to mark on the actual image, just bear in mind you will have to chop off the excess from that edge as well when you print.
Just thought, you may not be printing at all, and want to do everything digitally. In which case, I would just use the rectangular marquee to select each section (it shows the size of the selection in real time as you move it, or you can type in the size you want in the toolbar). Then copy and paste to a new canvas.