Heh. I had a similar idea to swap out the first real from the Return of the Jedi premiere with the one from Revenge of the Sith. Assuming no one stopped the projector before the crawl ended and the space battle begun. (It’s fun to drive people mad.)
You could theoretically write an app that used the speaker on your macbook as an acoustic modem. Then run down to your local Radio Shack and get the latest top of the line Tandy Trash, an acoustic coupler, and you’re good to go!
Of course you’d need to know all of your communication protocols, data formats, etc, but I’m sure that Apple has already thought of that in their OS…look for the icon that looks like a pink neon hamster carrying a snowglobe 