I don't have any comment about castor oil, just don't know anything about it, but I used to be a massage therapist and can give you some pointers to possibly help. (A friend of mine went into labor two hours after I massaged her). It would help if someone else could do it but you could very well reach these points.
Rub in between forefinger and thumb, rub at the oxiput just at the base of the neck, lots of foot massage, esp around ankle, do very gentle, circular vibration on belly welcoming baby into the world.
I didn't want to be induced either so I did acupuncture and that helped but I think my "problem" it that it was purely psychological: I wasn't ready until I was ready: )
Very best to you!!
Jen