So when I was watching this video from BUILD I thought it's gonna be easy...
But I can't seem to get the tile of my WP Silverlight 8.1 app to change by doing the following.
const string xml = "<tile>"
+ "<visual>"
+ "<binding template='TileSquareText01'>"
+ "<text id='1'>testing 123</text>"
+ "</binding> "
+ "</visual>"
+ "</tile>";
var xmlDoc = new XmlDocument();
xmlDoc.LoadXml(xml);
var tileNotification = new TileNotification(xmlDoc);
TileUpdateManager.CreateTileUpdaterForApplication().Update(tileNotification);
Please note I've also created a Windows RunTime Windows Phone 8.1 with exactly the same code and it works just fine.
On msdn, it clearly states that TileUpdateManager supports Windows Phone Silverlight 8.1. So I don't really know what's missing here.