Most supermarkets, including Whole Foods, have the tools to cut and core a pineapple and usually will do it when asked as a courtesy. It is easiest to remove the peel and slice the pineapple into 1" thick rings and then carefully remove the core ring by ring if a pineapple corer is unavailable. The spiced syrup may be made a day in advance—the flavors with intensify so adjust the amount of time the pineapple rests in the liquid.