People are always resistant to change, and moving to scrum is a pretty big one. Motivation and direction are key.

The first step is to get people motivated to give scrum a chance. I found that Ken Schwaber's Google Tech Talk has been very useful in getting people to recognize the benefits of scrum while providing a good introduction. Start with people who you feel will be receptive to the change whether they are developers or managers, so you can build some momentum. Getting managers on your side going to be a necessity at some point, but how you handle that depends on your environment.

After that, everyone needs to be trained, whether it means reading a book or having a lecture series. Unless people know how scrum works, you cannot start trying to implement the process.

Once people are motivated and have an idea of what they need to do, you need to have your first planning meeting and set up the necessary parts of scrum (scrummaster, daily meetings, etc.).

I would expect that the first planning meeting will not go smoothly, and will be a learning experience for everyone. Also the first few sprints will be very rocky, and probably behind schedule. The key part now is discipline and persistence. Do not let daily meetings run too long, keep the planning meetings on task, and make sure everyone is doing their roles correctly.

I think the people who are most resistant are people who have been doing software development a long time, or people who feel that by moving to scrum, they are admitting that they were doing something wrong before. It's a tricky obstacle to overcome, but I think by showing them the benefits you can slowly convince them. It just takes time. In my experience, product managers really are resistant because it forces them to be more clear about their requirements and what they want. But once they see how the agile process benefits them and makes their lives easier they get on board pretty fast.

Good luck!