I am surprised the MSF didn't include some freeway time. The Canadian equivalent does, and my licence test included getting on and off the freeway.
I would try driving to work on a weekend first - that is what I did. I am not sure when a quiet time would be, but pick the quietest and work up slowly.
+1 on weekend riding. The interstate is a pain. Remember your buffer zones from MSF course and after you ride for a while on the interslab you'll get so used to it but it is scary as hell at first.
+1 on the Canadian test! That's intense. Tennessee just requires you wear a baggy t-shirt or leather vest, a helmet, and the ability to sign the organ donor line on your license application.
I would suppose they don't teach freeway riding at MSF Basic Rider course because everybody can go fast in a straight line (*wink*). The goal of the MSF Basic Rider course is to teach you how to control the bike at lower speeds where it's more unstable and you're more likely to have to think/react quickly.
I think the Interstate is one of the safer places for a motorcyclist to ride because everybody is going the same relative speed, there are multiple lanes for emergency maneuvers, no stop lights / intersections and there are less surprises (dogs, kids, driveways). It is however very BORING. I envy you folks in Cali, Colorado, Wisconsin, etc... that have nice curvy roads to ride to work. I get 16 miles of interslab every moring. bleh!
Just remember: 4-6 seconds to the car in front, know your surroundings, keep a buffer zone, mind cagers blind spots and as my good friend with 40+ years of safe riding says "Remember: everybody in a car is out to ****ing kill you."