There are many pros and cons of mainstreaming students with disabilities especially depending on the school district that you are in. Some people feel that all teachers need to be better educated, or even properly educated to begin with, on how to properly work with a student with a disability, or multiple disabilities. One of the cons, is that when a student with a disability takes a mainstream class, they may not get or even be offered the one on one approach that some students with disabilities need to succeed in their educational goals.
On the other hand, some students with disabilities are advanced in some areas, and may be ready for the challenge of a main stream class. It really depends on the individuals situation, and circumstances whether or not they are up to the challenges that may come with being placed in a mainstream class. One thing that I have seen up close and personal, is that a student may insist on taking a mainstream class for the challenge, as well as to learn about a specific subject, and they sit down at the student’s IEP or Individual Education Plan Meeting, to discuss this with the teachers involved, as well as the parents to discuss whether or not this is truly realistic for the student to be taking on the challenge, and if so what else needs to be put into place to make something like this work. It is not out of the question that they could place the student in the class with maybe a note taker if that would help the student to keep up, and have the class lectures be recorded onto a Dictaphone so that the student could listen back to see if they missed anything or if they can not remember exactly what the teacher said they could refer back to the tape and see if they can find the information that they are looking for. Another thing that some schools do with these students is to have a study hall period right after the class in question, so that they can have another half hour or hour depending on how the classes are scheduled to work on the material that he got in the class he may be challenged with.
You should talk with the teachers involved, and find out what would be expected of the student throughout the course, and set a plan as to how these goals are going to be achieved. In addition to having a note taker come in and take notes for the student, you might consider getting a tutor involved so that the student has someone that they can work with one on one even outside of the classroom hours. If this goal is something that is extremely important to the student, do not try to discourage it, when you are working with someone with a disability, they more than likely have been told no or discouraged to try things all of their lives, and if this goal is something that can be achieved with a little extra effort, and a little extra work then there is absolutely no reason why they should not be allowed to try. It will give them a sense of pride and a sense of accomplishment even if they have tried and failed, and you never know, they could possibly even prove people wrong and really come out of the experience with a sense of pride and accomplishment that they have defied the odds and have done something that a lot of people said was impossible.