The fastest way to get a keg from the ground to overhead, would be the viper press, or muscle snatch. Keg lifting especially with water can be extremely awkward but builds great strength and stability for lifting awkward objects. Honestly the only way to know how to do the lif is to just try it, however there are a few thingsa you can do to train in the gym to get better for them. First, develope strong spinal stabilizers with heavy deadlifts, Zercher good mornings, sand bag clean and presses, and Axel bar cleans and presses are also great. However, here is a video of what a keg ground to overhead looks like.