Finally!

1- Append to file ~/Android/Sdk/emulator/resources/Toren1BD.posters
    poster custom
    size 2 2
    position 0 0 -1.8
    rotation 0 0 0
    default custom.png
2- Place 'custom.png' in ~/Android/Sdk/emulator/resources/
3- Restart! 
    emulator @Phone -no-snapshot -no-boot-anim 
    (replace 'Phone' with the name of your avd! (see: emulator -list-avds)
4- Profit!