Full text of CA Advance Directive Law is available HERE.

This includes a model form. I suspect it would be best to write it in longhand on paper so that the document could be verified by a handwriting expert, sort of like how you write a Holographic Will. California recognizes wills written in the decedent's own hand, according to Findlaw, so I suspect this would also be the case.

This also means I don't have to pony up money for an "official Advance Directive Kit." Or have a lawyer write it up.

I don't want to end up like Ms. Schiavo. If you don't want to, this is what you do. If you don't live in the State of California, look the info up for your particular state. Or your country. Whatever.