http://www.google.cn/search?complete=1&hl=zh-CN&newwindow=1&q=%E5%8F%AF%E4%B9%90%E9%B8%A1%E7%BF%85&btnG=Google+%E6%90%9C%E7%B4%A2&meta=google "Ke Ke Ji chi" in chinese and you will find many recipe on this dish. I never seen it on any restaurant, but many ppl cook it at home in HK/China.
Got many different version of cooking it, but they are all similar. No "perfect" recipe, if you prefer sweeter, more cola less soy sauce, if prefer less sweet, than less cola and more soy sauce.
Add enough cola to soak the chicken wings when you start cooking, at later part turn max fire to make it dry up, the chicken wing will be coated with a sticky layer of cola sauce.