I do not claim to understand why any doctor would refuse to honor a dying person's request for painkillers. I remember my friend Laurel who feared becoming addicted to morphine during the final stages of her ovarian cancer. I told her, "If you can recover from this cancer, I'm sure you can shake this addiction. Right now the drugs are keeping you comfortable."
I totally support each person making what must be personal decisions. The email from Compassionate Choices ended a link to a sample letter you can discuss with or send to your doctor, so you can have a discussion of your wishes before you need to act on them. Here's the download link: http://www.compassionandchoices.org/documents/DoctorLetter.pdf