I don't think you need to be too nervous at technical speaking engagements. In my experience, most people just show up to hear you say the name of the talk, and then they tune out and start using their laptop. So if you pace around the stage, they won't notice, 'cause they're off in some other world.

(You could say, "Well, that's because all your talks are so boring.". Maybe, but this happens at even the most interesting speaker's talks as well.)

Make sure to practice at least a few times in front of some friends to get the jitters out. I have to present once or twice a semester and I always need a few dry runs to get the jitters out. If I really was presenting to a large audience I would have to practice many, many times to have it all down pat and not look nervous.