Bad news: Blue & Black cohosh, acupuncture, evening primrose oil, copious amounts of sex, latin american tea blends --I tried it all. If your body, and more importantly the baby, isn't ready, then nothing (short of an ingorant OBGYN with a blade) will rush it.
Good news: Your body is preparing for labor. The more it does in preparation, the shorter time you will actually spend in hard labor. I had contractions for 5 weeks prior to the birth of my second. The last week felt like full on early or pre labor. That's probably what you're feeling. Two of those weeks were after the due date-- boy was I getting impatient! And grumpy! I know how you're feeling. But on the night of the 14th day post due date, I woke up at 1am in transition! 2 1/2 hours later baby was born. My first labor was 45 hours long and I wasn't dialated at all to begin with. Given the choice, I would much much much rather have weeks of moderate crampy labor and an intensly fast birth, than 45 hours of hard and exhausting labor.
Seriously, this is *good* news that you're having some pre-labor preparation. Don't let the blade happy OBGYN make all your hard work for nothing. Have some patience, and endure the few hours work that is birth and save yourself the weeks of recovery from surgery and your baby the exposure to pain killers.