Zeph,
I'm afraid you have a fairly unique request. I found some other issues dealing with something similar on another
discussion forum. However, I have questions on how you want to perform this synchronization since serial does not rely on a sample clock. The closest I think you could get is synchronizing the start time of both of the tasks, which you could do by combining the serial read/write examples found in Example Finder and your start task. Good luck, post back if you have further questions.
Sincerely,
Chris G in AE