I have been using the Image Overlay Module. Works really well on browsers like Chrome but the moment I open the app in a mobile device (ipad or mobile phone) when I do a pinch zoom the zoom action is interrupted.
I have managed to get a workaround by doing this in the pushpin Refresh:
// anchor: new Microsoft.Maps.Point(size.width / 2, size.height / 2)
_basePushpin._anchor.x = size.width / 2;
_basePushpin._anchor.y = size.height / 2;
But it looks ugly because the image overlay jumps a lot when rendering.