Scrape as much of the wax off as you can; you can put the sweater in the freezer for a while or you can put an ice cube on the wax to help.
You can put paper towel or brown paper bag on an ironing board, place a clean cloth on top of the sweater, then put the iron down over the wax. This will melt what's left and it will soak into the paper.
Eventually you'll just be left with a greasy spot. When you take the sweater to the cleaners, tell them what the spot is and what you've done to it already; they should be able to get the rest of the spot out.