I have seen there is the custom.zip this is yes, but empty, you could send me a sample that is ready-filled eg for WordPress or so. So I know how it works?
Sir are you looking for Custom script package ?
If yes here is the documentation on how to make custom package :
http://softaculous.com/docs/Making_Custom_Package and you can find the WordPress package on your server :
/var/softaculous/wp/