Congrats on the new spa, richie.....may the goddess of Spatopia bless you with crystal water.
Since my LSX sits on a deck, I wired it through the bottom by drilling a hole through both the plastic bottom pan and the deck at once. If you are sitting on a slab and need to go through a side panel, I believe you will have to drill or saw a hole through the panel as there are no knockouts that I have seen. I would suggest you fashion the hole in a panel immediately beside one of the corner panels. Another possibility to investigate would be to go through the bottom pan below the panels.
Good luck and let us know how it goes.