Not on a single room reservation. Everyone registered on a package reservation must buy the same dining plan for the entire stay. The only way to get around this is to book two separate room reservations, one with the dining plan and one without. That would not work too well with the 4 for 3 package deal unless you want to add a couple of days onto the week's stay, but you'd have to get the dining plan for the entire 7 night stay on the package.
If you don't want to schedule dining reservations, but you still want your dining prepaid, you might consider the quick service dining plan which can be supplemented with a couple of OOP table service meals.