Let's see if I get the menus right here:
Download the inch^2 image, open it in Photoshop. Use the "Select All" function and under the Edit menu (I think), select "Define Pattern". Then go into your new image, hit the Edit menu again and select "Fill". When the Fill submenu appears, in the "Fill With:" pulldown menu, select pattern. Click OK, and you're done.
Have fun,
brendanc@icehouse.net