MDM configuration (linuxmint theme)

Another instalment of the MDM customization.
Specifically on the Linux Mint theme (/usr/share/mdm/themes/linuxmint/), which IMHO, is the best one.
As I already posted before, I hate, truly hate, when the wallpaper I'm using is not globally set, that is, when there is a different wallpaper on the login screen than the one I use on my own session.
So, this is what I'm doing:

cd /usr/share/mdm/themes/linuxmint/

And make a backup of the original file:

sudo mv  background.jpg background.jpg.ORIG

And then link to the image you want:

sudo ln -s /usr/share/backgrounds/linuxmint-qiana/mattbuck007_8263284303.jpg\
background.jpg