May I ask why you don't want to use regular beer? I'm curious.
I wish I could be of more help, but my aunt loves to cook beer-in-the-rear chicken using real beer, and at first I had concerns about the beer part, as I'm not old enough to consume alcohol legally, but she assured me that after the chicken was cooked the alcohol would have no affect.
But the suggestions that other people have put in sound interesting. Dr. Pepper sounds interesting.