You said 'could always look at maps'.... I think that's what I would advise. :)
From Banff go to Jasper then to Prince George then 97 to Dawson Creek (Alaskan Hwy) to Fort Nelson to Watson Lake to Whitehorse.
On your return at Whitehorse to Watson Lake take 37 south (the Cassier Hwy) to Prince George.
You can't get lost - there are very few main roads to get to Whitehorse.
Get the Milepost for good history information and maps; Mike and Terri Church's book 'Alaskan Camping' which includes Canada and the Yukon; and the TourSaver 2/1 coupon book online before you go. That's all you'll need for the trip. Have fun! It's a long one but not difficult.