Well, I'll throw a suggestion in here even though I'd probably avoid this installation myself. Why not just gently chip out the grout around one single tile, then pry the tile out from the wall? After that's done, you can cut a smaller hole in the backer board or gypsum board behind it, cut in a low-voltage mounting ring and place a one- or two-gang face plate with a single hole in it to dress it up.
HERE is a link to the type of plate I'm talking about. In a commercial kitchen application, the health department will probably require that the opening be sealed with 100% silicone caulk once the cables are run through it.
Of course, you should save the tile(s) removed and keep them somewhere nearby in an envelope or something for use in the future if the hole needs to be covered back up or if they need one elsewhere.
As far as regular holes, say about 1/4", all you have to do is use a punch and lightly tap the center of the hole enough to chip the tile's glaze finish. After that, a brand-new 1/4" masonry bit will do the job. Just don't press too hard or go too fast, like everyone else has already mentioned. Don't count on using standard plywood though; wood is generally not permitted in these areas. You'll probably need to get a piece of poly plastic for your backboard.