Hey, mate.There's a handy tutorial in the Trisquel docs: https://trisquel.info/en/wiki/customizing-trisquel-iso
It looks like that'll let you do what it seems you want to do.I can't help but think that it would be simpler (if the ISO would only be for your own use) to install the software semi-manually every time you installed Trisquel. Like a shell script that installs the packages in one long or multiple "apt-get" commands.