I'm going to disagree w/Ken on the acclimatization strategy. Usually, you are OK the first day, then not so ok for at a few days after that, and then get gradually better over the course of a few weeks. Since you only have a week, forget about acclimatization, you don't have time. Just make sure you drink a lot of water and not very much alcohol, and have fun. Low gears is a good idea. Advil or something like that for the headache. Sunscreen.
The big mountain passes (Loveland, Vail) tend to weigh in at 6-8% grade, with occasional little bits of 10%. Not very steep, but miles and miles of climbing. Can't help you with the hill training where there are no hills.... intervals? thousands of repeats on the freeway overpass? move?
Don't forget your camera. It's beautiful there.