slackbuilds_ponce/desktop/pspshrink

pspshrink (ISO compressor for PSP games).

pspshrink it's a GUI for converting PSP game images to .cso format.
It allows you to shrink your isos to the cso format which is compatible
with Devhook.

An alternative to pspshrink is "ciso", a command-line tool also available
on SlackBuilds.org.