Instructors and presenters don't have to change anything about their presentation methods to accommodate transcriptions services. Any accommodations they are already making for a deaf or hard-of-hearing person in a class or meeting will benefit the transcriber as well. (These include such accommodations as not talking while facing the board, speaking clearly, etc.)
Instructors and presenters do have to allow the transcriber to sit where he or she can hear the main speaker and others clearly, and instructors and presenters should not show any lack of support for the service. It is very helpful if the instructor or presenter gives the transcriber a copy of readings and any handouts for the class or meeting. The transcriber uses these materials to prepare for the transcribing assignment.
The instructors/presenters also need to ask all the participants in the class or meeting to speak loudly and clearly. It is often necessary for the instructor/presenter to repeat what a person says so everyone can hear and understand it. This repetition helps the transcriber and all the participants.
Instructors should be asked to look over the transcribed notes at least occasionally, to verify that the content of the information is accurate. This is especially important in technical classes.
Other than these few things, instructors and presenters can just enjoy having their classes and presentations transcribed. Some of the benefits for an instructor include having a record of what was presented, having a resource to give students who missed a class, having a ready way to tell a substitute instructor what was covered the day(s) before, and having another tool to help any and all students with special needs to learn the material presented.