I would practice your part a lot. having it down pat will be one less thing your brain has to worry about. Secondly, i'd do my best to keep things slow and steady as you speak. for me, once my nerves get ramped up its almost impossible to calm them down again so focus on not *forcing* yourself to speak quickly, to blurt words out, to "try hard". A technique that helps a lot of people before a presentation is to disclose their stutter. Just something quick like, "Before I begin I'd just like to let you know that I stutter. If anyone has any questions or needs clarification i'd be happy to take them at the end." Something along those lines. It can put you at ease and the audience at ease.