Kathy, that's something a lot of people would love, but the new transitions are a totally different breed from the standard ones. They're actually more slide style than transition. If one was placed in a layer (just supposing it could be), it would be equivalent to trying to apply a slide style to just a single layer. Imagine the chaos if you applied a slide style to a slide and then applied a slide style on top of the slide style.
Our only hope is that Photodex gets inspired one day and comes up with more doodads for us to place at the beginnings and ends of layers. However, we probably shouldn't hold our breath.