It's a regular well maintained paved 2 lane road. Emerald Lake is 75 miles one way from Skagway. DEFINATELY- reserve NOW if going this year, only major is Avis, and I do not recommend the only independent.
Print out and take with you Murray's wonderful, road log and follow along. Allow 4-5 hours. If of interest in dog sledding, stop at Caribou Crossing, cart rides available. http://www.cariboucrossing.ca/
Drive from Skagway to Emerald Lake is beautiful - and most definitely you should print out Murray Lundberg's mile-post guide prior to your cruise.
We rented car months in advance from Avis (a short walk from where our ship docked). The drive is very easy and you can take at your own pace. We managed to see lots of "wild" life along the way. The scenery is just beautiful - and Murray's mile-post marker guide was invaluable for the trip. (Thanks again, Murray.)
There was plenty of time after turning in the car to see the sights in Skagway - though I don't know what your ship's schedule is.