I'm afraid that joint compound might not adhere well to plywood.
It will stick just fine. I have painted wood paneling this way too...by taping all the seams just like you would dry wall, and filling the grooves as well. Once it is sanded and painted it looks just like drywall.
Joint compound will adhere very well to the plywood, but the movement of the plywood from temperature and humidity changes will cause the compound to crack. If this is an issue, batten strips may be the answer.
