Unless you order your ham spirally sliced you are going to have to slice yours at home, and no you can't do it in a spiral. For that you need an expensive machine called a spiral slicer which spins the ham, while a spinning blade makes a continuous cut. Those of you running to the garage for a circular saw and your old turntable, just clear that thought from your mind, we're going to use a cutting board and a knife.
To be specific we are talking about slicing a city ham, not its country cousin. Country hams resemble prosciuttos and have been aged for months to years, resulting in a salty smoky delectable ham. As a point, let's all agree to avoid ham that comes from a tin. City hams are the pink moist salty sweet staples of Christmas and Easter, usually glazed or oft decorated with spikes of clove and pineapple rings. 
They are made by brining (soaking in or injecting a salt and nitrate mix) and then cooked with or without smoke, the process can take from 2 days to 2 weeks. Usually City hams are split in half at the knee, resulting in a butt end or a shank end. Some prefer one and some prefer the other -- it's a matter of taste and doesn't matter much when talking about carving
Carving a Ham
While canned hams are easy enough to carve for anyone with a sharp knife, bone-in hams are a bit more challenging (giving rise, no doubt, to the popularity of the spiral ham, which comes presliced). The leg bone is pretty much in the center of the ham, which means you have to cut around it.
Whole cooked bone-in hams come in all shapes and sizes. When deciding where to start carving, look at the face of the ham (the largest end) and choose a spot that is narrower than your knife is long. Examine the ham to find a flat surface to rest it on. If you need to, cut a thin slice off one side.
How To Carve A Ham
Jeffrey Elliot is The Executive Chef and Director of Culinary Relations of Zwilling J.A. Henckels and along with James P. DeWan is the author of the Zwilling J.A. Henckels Complete Book of Knife Skills: The Essential Guide to Use Techniques and Care.