in PS:
-open new doc
-draw a tile
-convert tile to a smart object
-instance that smart object 8 times to create a 3x3 block of your tile
-zoom to desired zoom level
-make a new window for any doc at any time, set it's zoom level accordingly (this serves as an additional "preview" window, DO NOT USE the navigator panel)
-edit any one of the smart objects in another window
-see the changes occur in original doc, to all 9 tiles, everytime you hit CTRL+S while editing any one of the smart objects, and subsequent new windows of the original doc, if you set them up.