Joe Abley
You want to fly to AKL, and rent a car. You can drive from Auckland to Hamilton in an hour or two, depending on how heavy your right foot is. Aim for State Highway 1, head south, and get off when you start to see signs saying "Where it's Happening" [*]. You should be able to follow the signs to the university once you're in Hamilton, and there are campus maps on www.waikato.ac.nz.
If you're heading for the university from AKL, I'd pretty strongly recommend using the Gordonton road. When you get to Taupiri (just south of Huntly), there's a left turn, with a big green sign indicating Cambridge, (State Highway 1A). Take that and follow your nose. (Don't take the subsequent Cambridge turnoff some distance down the road.) The road ends after a long straight 50km/h zone through the outskirts of Hamilton. Turn right (left would take you into the Ruakura research campus -- that used to be a shortcut but I don't think it is anymore), drive a short distance to Peachgrove Rd, turn left across the railway line, left again. You're basically headed straight for the University at that point. Right at the roundabout puts you in Knighton Rd and all the western gates to the University. Left-ish, and right at the next roundabout, and right again at the turnoff at the top of the hill puts you on Hillcrest Rd, and the eastern gates. Easy-as, and you don't have to crawl though all of Ngaruawahia, Horotiu, Te Rapa and the whole sluggish bulk of Hamilton. -- don