Change the screen lock background

Question

I am trying to change the background image of the lock screen from my application, but cannot figure out how to do this. I managed to change the desktop wallpaper using WallPaperManager, but could not find a source that would do the same for the lock screen. I know apps like QuickPic and Gallery Gallery, so how can I implement it?

Here is the code I used to change the main screen:

WallpaperManager myWallpaperManager = WallpaperManager .getInstance(getApplicationContext()); try { myWallpaperManager.setBitmap(bm); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } 

Can anyone who has done this point me in the right direction to do this with my application?