I would do it this way. In Photoshop, (other programs will I think be similar), Edit/Select All of the tile image. Next Edit/Define Pattern. Now open a new document and use the paint bucket tool set to "pattern" to flood the whole area. By using different sizes of document you can get the scale you require. Save the image and apply it to a flat plane in Poser.

Another good tip to remember is that when laying floor tiles always start at a point furthest from the door :)