"Why can't the data in the WorldMapKit work" what does this mean? The OpenStreetMap using totally different data with WorldMapKit, I don't understand what do you want.
If you want to make the OpenStreetMap work and routing with it, it's not complex, you can refer :
Know how many data the OpenStreetMap have and how to get it from our server, then use ShapeFileFeatureSource to build the routing file for each OpenStreetMap data, after that, you can refer routing HowDoISample, it's totally the same now, you have the shape file, you have the routing file, you just make the simple route.
If you want to use OpenStreetMapOverlay directly make the routing, sorry like I replied in your another post, it's impossible.
Feel free to let us know your queries.