yes you can, you can be a special student until they recieve your TOEFL score and give you your offer.
but to be a special student, you can only take 2 courses each term at OU. That means you will be a partitme student. If you was a full time student in last two terms, you dont worry about it. if not, you can be a special student at Carleton and take other two courses in Carleton at the same time.This case is only for international students.