Hi David,
When I did mine I lowered the back seats, took out the parcelshelf and the deck board. Then lifted one corner to an angle and eventually the original polystyrene 1 section box came out. Lot easier putting the new in only piece that had me scratching my head was the piece that goes underneth the wheel but eventually placed i where it needed to be. Put the wheel and bits in, putting the original tyre pump and sealant in the right hand cubby, job done!
Hope this helps.
Chris.