The pumps we generally use for palliative patients are sc but they can be attached to central lines as well if pt's have them. They're called CADD pumps and work by delivering a continous dose of pain med plus having a "dose" button that pt, family or staff can press to give a breakthrough dose when needed. The dosing really depends on the pt's baseline narcotic dose and will obviously be adjusted as needed.
As for inhaled morphine we do use it from time to time. Sometimes it works, sometimes it doesn't. Usually for really severe dyspnea we'll sedate the patient with versed, either intermittantly or a drip.