I, too, am going into my OB/Peds rotation, and am also ethically opposed to forced circumcision. I will observe, but till not participate or help in any way with the procedure.
This is the only legal procedure I would ever refuse to participate in, BTW. All other procedures I have thought about, the patient can consent. In end of life care, while I may disagree with a choice (usually to extend life despite suffering), I could still carry out the family's wishes, etc.
But not with infant circumcision. Won't do it.
I do not anticipate any problems with my nursing school or instructors. They have been very open minded and tolerant, and I do foresee any drastic change from this mode of thinking on this issue.
I plan not to say anything until I am asked to participate, in which case I will politely decline. If asked, I will say my moral code dictates that I not participate in infant circumcision.