The IEP should address the goals and the benchmarks to reach them. But usually the IEP does not address specific strategies (unless there is a very specific need, such as an audio device or something) because often strategies will need to change to achieve the goal. My son also has Asperger's, and his best teachers have been those who "switch it up" on him. He tends to learn how to manipulate their systems, so having a specific strategy defined in his IEP would backfire.
However, if you want specific strategies, you certainly have the right to request that. You are in charge when it comes to the IEP.
IMO one of the most important aspects of the IEP is to protect the child. If there is a problem, it is important to have that issue covered by the IEP so that it does not escalate. For example, if writing is a problem for your son, you will want to make sure the IEP calls for accommodations, such as shorter assignments and/or extra time and/or alternative means of submitting work. That way no teacher can decide to be a stickler about deadlines or paper length and refuse to allow your son to modify as necessary. But for things such as behavior modification, a little more fluidity can be helpful so that the teacher can access a whole "bag of tricks" to find systems that work for your child.
Sorry if I was too convoluted. We have our triennial tomorrow, but I still get flummoxed by IEP meetings. It is so difficult to know what is right for our children.
DS '04 "Boogaboo"
DD '08 "Lilybear"