Custom Ubuntu Mate livecd iso with Cubic

Good morning to all
I'm trying to create a custom Ubuntu Mate livecd iso with Cubic.
I would like to add to the Top Panel of the livecd some program icons.
When I get to the Desktop just right click on the bar and add to the Panel but in cubic I have to do it from terminal and add it to the /etc/skel/ folder.
How can I do this?