I don't think it would be hard but finding the right zipper length might be a little difficult.
Some one said to use a zipper foot when installing zippers. What is a zipper foot?
See the linked site. Basically a zipper foot is a narrower presser foot like a single ski that holds the material down. The foot is what you raise and lower to the material. A zipper foot allows you to sew closer to the edge of the zipper. http://www.sailrite.com/Tips/zipperfeet.htm