I'm sorry for the delay, it took me awhile to type this, and I had to do some research first, since I'm familiar with laws in a different state. I just spent some time reading California special ed laws, and as I suspected, they have to follow federal laws for students with disabilities as well as No Child Left Behind. The IEP has to follow a certain format, and the IEP team has to make as many adjustments as possible to keep each child in a regular classroom, rather than in a special ed class. If you want to read all of this for yourself, here's a link:http://www.sccoe.k12.ca.us/depts/selpa/iepforms.asp
Once you get to that site, you can click on other links for downloads on the 7 step IEP process, etc.
What all of this means is that it is most likely your administrators' hands are tied, and so are yours. Of course, you do have the right to read the IEP before signing it. If you feel you can't provide what they are asking you to do, you can also make recommendations of steps they can take to make it possible to provide for this student, for example, you could request a full-time teacher associate in the classroom for the student. You can't force them to do this, but you most certainly can make requests and recommendations. I wish I could tell you that you have more power in the matter, but unfortunately, you don't. If you actually refuse to sign the IEP after reading it, you could face disciplinary action, as unfair as that may be.
To me, it sounds as if this student probably would be better-served in a special classroom. But that isn't being realistic. The parents can, and probably would, decline that option. Because of the laws, the IEP team wouldn't consider it either. The climate of special ed has changed in recent years because of federal requirements that students be kept in regular education classes as much as possible. No one on the local level can do anything about that.
If I were you, I would read the IEP thoroughly, take some notes on what you feel you can't provide and what measures would assist you. Then ask a supportive administrator (I hope you have one) to accompany you as you meet with the IEP team - or perhaps just a key member- to discuss your concerns. After the meeting, regardless of the outcome, you'll probably have to sign the IEP and live with it.
You should keep the administrators updated with your concerns about the student, and about the other students as the school year progresses. If an associate to help the student isn't provided, you could approach your teachers' union rep about that.
I know this doesn't help you very much, and I feel bad for you and the other students in your classroom, but for good or bad, the law is the law. I do hope that at least you can get some support in working with this student.