In 10.1 ArcGIS Server, they have provided PrintingTool, which ArcGIS API for Silverlight v3.0 expose as a PrintTask. You can look at this SDK sample: http://resourcesbetadev.arcgis.com/en/help/silverlight-api/samples/start.htm#ExportWebMap. Is the route event layer a GraphicsLayer? If yes and it has a renderer/symbol that REST API support, PrintTask should be able to handle it. You can check the sample to see if this is something you could use.