How can you fix tiles that are rough and cause injury without removing the water from your pool?

Removing the tiles and old grout is a dirty and difficult job with the water still in the pool. It has been done. It is just as difficult to install the new tiles & grout. I have of some doing it from inside a small boat in the pool with the water lowered. Have heard of others doing from the deck working up side down, if you will, to set the tiles.