Your post is lacking info. Where will you actually be driving, the Al Can is a long highway.
I am not sure where your going to drive. But if from Valdez to Haines, these rules cover just about anywhere in Alaska. Except near Anchorage. Drive only in the day. Leave Valdez very early, you never want to be on those roads after dark. If it's starting to get dark and the next motel is only 70 miles take the hotel before it gets dark, even if it's 2 hours of lost time The temps from Valdez to the Haines cutoff can reach -70. This is true of just about anywhere on the Alcan of Richardson Highway.
Make sure you have a sleeping bag rated for -40 and another one, forget it to put inside that good one and enough wool clothes that you can stay warm if you have a breakdown. For 24 hours.
Traffic is almost non existent and if a big storm with winds you could be stuck for a day. If you break down . Do not leave the car. Have road flares.
Check in Glennallen the pressure in your tires. You will be leaving Valdez where it is probably 20 degrees and going to minus 50 to 70 easily. Tires will go almost flat in temperature differences of that extreme. Carry a quick patch kit and a can to re-inflate your tire if you pick up a nail.
Find a piece of cardboard to cover your radiator, unless you live in Alaska and have a winter temperature thermostat in your radiator , you will not get heat. Which causes your windshield to freeze up. By putting the card board or better yet a custom fit cover for your vehicle that you can zip open and close the air will not allow the water to heat high enough. You did not say type of
You might be able to do the drive in a day if you leave Valdez to get to Haines, again your route is not clear but the advice is for any road in Alaska or Canada . As of 1 -02-07 you will need a passport to enter and leave Canada and Mexico. Keep that in mind.
If your driving further then Valdez to Haines. Make sure everything in your car is top notch. If the battery is older then 3 years , get a new one, the one with the highest cranking amps possible, at 30 degrees your battery cranking amps is about 40% of rated capacity, at -40, well guess.. a battery blanket is a good investment a battery can freeze and the plates break. if you do not have a oil pan heater, get one, also a block heater. It will more then pay for itself the first time you crank your engine at -40 and the metal just goes grinding on your piston. Even 10 weight oil is like peanut butter. With the heaters all my vehicles have gone well into the 200K range.
If your coming up here from Washington, check the owners manual for the recommended weight of oil in your your rear differential, the often use a single grade 120 or 130 much too heavy for Alaska. Also the grease on your bearings for the wheels check the manufacturers recommendation. I have drive the road round trip 7 times and 2 in the dead of winter.
The conditions of the roads are good, at 50 below the snow is like concrete. I used studded tires. I also carried chains, just in case. Also a tow strap, jumper cables and they have these jumper battery that you plug in and they can help jump you in a pinch. In general never shut the vehicle off, it is very hard on metal to shut it off eat lunch and start it. Better to waste some gas then stress the metal.
Valdez to Haines you will see traffic, if continuing on the Alcan from there things start to get 50 to 70 miles between gas.
Any more questions let me know. Just remember Alaska does not have a rescue behind every tree. Your on your own and don't even try to stretch your vehicle, if there is something wrong -50 will find it and eat it for lunch.
Otherwise it is a beautiful and remarkable time of the year. Just be prepared and things will be fine.