Probably one of the best resources you could have is devouring every square inch of Matt Carpenter's website: http://www.skyrunner.com/peak.htm
You'll find some helpful tips for those coming from the flatlands.
Otherwise, here are a couple tips based on my own experience of doing the Ascent the last 2 years...
1.) Make sure you get your long run up to at least 2 1/2 to 3 hrs at the very least in order to get your body accustomed to being on your feet that long. Most-likely it will take you longer on race day.
2.) Don't neglect the speed - hit the track for some lung-busting repeats and do some 3-4 mile tempo runs to work on turn over. This is something Mr. Carpenter himself recommends
3.) Find the meanest, steepest hill in your area and make it your best friend, even if that means driving a half hour to get to it. If you use the treadmill, get used to running or hiking at 9-12% grade
Wish you well in your training!