Not sure I understand isolst. The iso boot code and fromISOfile already handle access to inside an iso image file.
Why do we need cdelst as it would not be convienent to enter such using cdrom.
CorePlus was designed to be an installation disk not a live distro. cde signals that such is to be treated as read-only so too would be any such list such as the installation lists used by tc-install.
If the medium is writable then should be using tce or a named tce directory. But, perhaps, I do not understand your requirements.