Hi KJS--
While I'm not an expert on IEPs...I think some of the answer will depend upon your SD and exactly what level of service you are requesting.
We recently revised my son's IEP rather informally...sending a few emails and exchanging phone calls. Everyone was in agreement and since it did not require the school to do anything major...the changes were put in place without a whole lot of formal documentation.
At our old SD, however, any little revision had to be formally documented and reviewed by the Special Education Committee. It was like pulling teeth to have anything changed.
Hopefully, your SD is the "easy-going" type--but if not, be prepared to go through a formal meeting process to get the revisions you are looking for.
Best of luck!
--DaisyF