I am trying to create a Live Tile with a different layout that the ones defined in the tile template catalog. Specifically, I want text to appear on top of an image for the 150x150 tile. Is there a way to do this for a Windows 8.1 app? I do not see this template for that size. Thanks
http://msdn.microsoft.com/en-us/library/windows/apps/hh761491.aspx
if you want to create a custom live tile you have to create image and use it as a background for your live tile.
Take a look at this post: http://spasol.wordpress.com/2013/06/24/creating-custom-live-tiles-for-windows-phone/ the Update Live Tile with custom parameters section.
Additionally If you need to update your live tile using background task you need to use http://msdn.microsoft.com/library/windows/apps/windows.ui.xaml.media.imaging.xamlrenderingbackgroundtask.aspx
