Hm. I think this might have actually worked.
It's a really short sound file of Dean and Sam both speaking latin simultaneously. About seven seconds long. Best on headphones, Sam will be on one side and Dean on the other. I wish it was longer, but Meg starts beaking off in the middle of Sam's bit from "Devil's Trap", and the musical score on Dean's bit from "Crossroad Blues" is quite distracting, but I think I got an okay effect. Please let me know what you think, I haven't really done anything like this before! :-)
Download 'simulatination.wav' file here (1.3mb wav) Keep hitting the 'next page' link on the page that shows up and it will get you to where you download the file. If it's disappeared (which it will if not downloaded by someone every thirty days), let me know and I'll re-upload it. (link expired, ask and I'll see if I can reupload it somewhere or e-mail it.
Wav seems to load in Quicktime and iTunes plays it, so hopefully people will be able to hear it.