Here are some rough first draft ideas.
Day 1 Starting point, Kamloops BC. to Vanderhoff 620 km, Motel
Day 2 Vanderhoff to Stewart 600 km, Motel
Day 3 Stewart to Watson Lake 640 km, Motel
Day 4 Watson Lake to Whitehorse 439 km, Motel, Hotel, Inn
We may stay longer at select destinations to view the local attractions, this is all still open to suggestions. Hyder Alaska, 90 km from Stewart would definitely warrant an extra day to view the glaziers and Grizzly bear habitat, as well as getting Hyderized.
Stewart, B.C. - YouTube
http://dglamb.smugmug.com/Travel/Stewart/12744741_kfS5QN#!i=917965796&k=VJChZLn