My daughter is almost 6, and is pretty picky about soy products (and everything else, actually). She hated soy yogurt until recently, when I started freezing it. I buy the six packs of Silk yogurt, shake them up to mix everything around, and stick them in the freezer overnight. I can even call them "dessert" and she's happy as can be about eating them. I also stick them in her school lunches and they're still partly frozen by lunch time and she likes that as well.
Just thought I'd share! Not a cooking tip, per se, but a preparation tip.