OK, this will be a lengthy post, so I will apologize in advance. So here goes.
I've done the Alaska Hwy numerous time, but never on a motorcycle, though. It's not that big a deal, in that the road is generally very good, high-speed paved highway. There will always be a sections where they are repairing places that have been damaged by frost heaves, but unless it's raining hard, those areas are easily traversed. Any motorcycle in good condition can easily make this trip. Fuel is available during the summer months every 100 miles or less, as are accommodations and food. Admittedly, if one is motelling it, some of those places are, how shall we say, quaint? But it beats sleeping out in the rain on a plastic picnic chair. Places to camp are numerous.
The road to Alaska is mostly long--2500 miles from Seattle to Anchorage, to be exact. It's a longer trip if you come from farther East. As for its toll on the motorcycle, it shouldn't be any worse than taking a similarly long trip somewhere else. In short, it's not the frontier adventure that it was, say, back in the 60's and 70's before it was paved and sections relocated.
My personal recommendations for bike preparation for such an undertaking would include starting out with a fresh oil and filter change, new air filter, and new tires, as you are going to put on anywhere from 5000 to 10000 miles on an Alcan trip. And don't forget, you have the entire Alaska road system to explore, as well.
This trip shouldn't be any harder on the bike than any other. I always suggest not trying for marathon mileage days, (unless time is of the essence) and just make it a leisurely ride so as to enjoy the scenery and wildlife along the way. You will see all sorts of game, including bear and bison, as well as the occasional moose, and in southern BC, elk. I can almost guarantee that while going through the Stone Mountain area and Muncho Lake, you will see caribou and mountain sheep on or next to the road. Makes for great photo ops. So do carry a good, yet compact digital camera with you, as well a couple of high capacity SD cards, like 16 or 32 gig cards, because you will take lots of photos.
Take a cell phone with you, and most carriers will have a Canadian access feature that you can sign up for, then cancel at the end of your trip. Otherwise, calling from within Canada will be seriously expensive. A GPS is a good thing to take, but once you are on the Alaska Hwy, there is only one road and one way to go, so you can hardly get lost. It is good for letting you know how far it is to the next location, intersection, etc. If you have a late model Garmin, it may already have the Canada data in it. If not, it can be downloaded. I don't know about any of the other brands.
As for gear to take/wear, take and wear what you normally do anywhere else, but I would add that it can get pretty cold at night from time to time, and having some electrically heated gear is a blessing when starting out on a cold morning. Gerbings and Warm & Safe are two good brands that work well and keep you comfy when it's cold. Rain gear is essential--raingear that performs, that is, not rain repellent. I can't emphasize strongly enough that you can't beat GoreTex gear. Its' expensive, but worth it on an all day ride in the rain. Make sure you have boots that are 100% waterproof, or have rubber rain boots to slip over your regular boots.
There are mosquitos!!! Lots of voracious mosquitos and they are just waiting for some unsuspecting person to come along, for a feast. If you wish to donate blood, go to the Red Cross. Otherwise carry along some good insect repellent, and up here, make sure it's 100% deet!!!! It's the only stuff that works adequately.
Finally, if you are planning an Alaska trip, start out your planning by picking up a copy of "The Milepost." It is the "bible" of the Alcan. It's updated annually and the information is exhaustive and accurate. From that you can determine your route up here and what there is along the way. Should leave you with no surprises along the way. After that, ask questions. I am always open for questions and will do my best to answer them, especially questions about Alaska riding and what there is to see up here.
"Don't sweat the small stuff---it's all small stuff"
'09 650 VStrom