Here's my TR of our "unsuccessful" attempt on Denali in 2009. "Unsuccessful" in that we did not summit... but a huge success in terms of a once-in-a-lifetime experience I'm so glad I had.
The link to "The Plan" (in the first line or two of text) talks about our training and prep, permits, gear, schedule, etc. etc. etc..
Glad to answer any questions you might have. Sean made it to the summit, and Tom was with me. Both frequent this board and might chime in.
Note that you do NOT have to train like a mad man for Denali. It helps to be fit, and you'll enjoy the trip more if you are ready for some good hard labor, but altitude requires that you go slow. As some say, "You camp your way up the mountain."