I second what Ashley said above. I just graduated in May, but I started out my very first semester by finding who the "oncology teacher" was in the program. I met with her to discuss wha opportunites she thought might be available to me as I progressed through the program, then when I got into the class where she taught, I requested that I be put into her clinical group (not supposed to request, but I did it anyway and maybe she had a say in the decision) and made sure that I was able to go to the hospital where she had "ins". Then the final semester, I was given the option to choose what hospital I wanted to precept at and I chose the one where I had already done the clinical and requested the oncology floor. When I actuall was on the floor I made sure that every nurse that I came into contact with knew I wanted to work there and I made sure that my skills (clinical, technical and social) were beyond reproach and I passed out my resume to the supervisor, manager and director of oncology (pretty much anyone who would listen). But I didn't do it in pushy way, I was professional, but let them know how much I was interested. Within 2 weeks of my preceptorship ending I was interviewing and then offered a job on the day of graduation on the floor I wanted, working with the nurses I wanted to work with, so it can be done.
I can't stress enough how professional you need to appear and not get bogged down in the "social and gossipy" side of the nursing station. Oncology is serious business and they are looking for serious nurses who know what they want and what they can contribute to the unit. I wish you good luck, if I can do it so can you.