I truly adhere to the No-Blood doctrine. (even though I don't adhere to much else at the moment)
I'm not sure I understand why you're adhering to some of the JW doctrine, but not all. Why worry about getting a bit of blood if there are other things you allude to doing that may be mocking Jah. Just a thought.
But, to address your question -- what the others have said. You don't need a "blood card" from the JW to make your medical wishes known. Contact your attorney, or do a google for a 'make your own' POA/living will document. Two witnesses or a notary to sign it and you're set. And yes, if you want it enforced in an emergency, keep it with you -- next to your driver's license; it's the first place paramedics and medical personnel look when you're in that situation.
I know the JW version of the card has a lot of "yes this fraction, no not that fraction" and treatment choices that JW are encouraged to "research" in order to make a decision. http://www.ajwrb.org has much info on fractions etc. I encourage you to start your research there.
HTH!
~merfi