Maybe one of our resident midwives can answer - I know we had them on Pampers, not sure if they moved with us

and p.s - it was drinking castor oil, not olive oil

But, I have read now that it can cause dehydration in the mother because it causes diarrhea and can cause the baby to pass meconium or it's first bowel movement which can be fatal or cause serious harm to the respitory system - so DEFINITELY not a good idea.
I found this on the internet but really, I don't know how safe any of it is:
Using nipple stimulation to induce labor has been practiced by women for centuries. This stimulation brings about the release of oxytocin, which is the natural form of pitocin. Oxytocin causes contractions, which can lead into true labor. It's important to note that this will only happen if your body is already close to labor. As with all natural labor induction techniques, don't attempt this until you are over 40 weeks.
It is a practice often recommended by midwives when a woman is long past due or when labor is stalled. It causes the release of oxytocin, the same hormone that causes uterine contractions. This can be done manually or with an electric breast pump.
When this is performed, the uterus sometimes becomes hyperstimulated, meaning that it gets too little rest between contractions, so use caution and consult your practitioner first.
Here is a guide to help you understand the process:
Only massage one breast at a time.
Grasping the areola, rub in a circular motion until a contraction begins. It's important to mimic the suckling action of a baby.
Stop after the contraction begins.
Wait 15 minutes, then repeat.
Stop using nipple stimulation if the contractions are 3 minutes apart or lasting 1 minute or longer.