What does the manual clearing of mucus for children with PCD (or cf, which I've read is similar) involve? Is this something I would do daily at home?

Chest physiotherapy. Clearing mucus from the lung can be done by effective chest physiotherapy. There are vests available and valves which create pressure to help clear the mucus from the lung. One link that you may find useful is thevest.Com and also checking with the cff.Org for information. Prmg will rev records faxed to 8582599689.
Respiratory therapis. Speak to your pulmonologist and they can have a respiratory therapist show you how to perform this. If you get in-home aid, they may also be able to send someone to you. Good luck.