Once your pitch forks are securely anchored in the center of your perennial, simply pull the handles in opposite directions, away from the center of the plant. Again, you will hear cracking. The roots will not be breaking cleanly, but the plant will recover.
Sometimes a densely rooted plant will resist and it will take two people to pull the forks apart and split the plant. And as mentioned in Step #5, exercise caution, since garden tool handles can break and send you tumbling.