Mkisofs
From MohidWiki
Mkisofs can create an iso9660 or Joliet compliant image from any directory of your linux system. Useful to create a new iso image after copying and editing an existing iso image.
Syntax
> mkisofs -o myimage.iso -J /home/user/datadir
Bootable cd iso images
From a modified linux cd installer directory ( after having performed a "cp -a /media/cdrom0 ~/tmp/cd"):
> sudo mkisofs -o debian.iso -r -J -no-emul-boot \ -boot-load-size 4 -boot-info-table \ -b debianlive-custom/isolinux/isolinux.bin \ -c debianlive-custom/isolinux/boot.cat \ ./debianlive-custom/