I have customized a LDAP authentication module for CATS. However it's not complete and many improvements can be done. Even though it's developed for cats-0.5.5 it works fine with the 0.9 also. you can download the patches and files from here:
The user list is still maintained in the mysql table, but the authentication request will be directed to the ldap database. To create the user first you
have to add the user to LDAP and then to the MySQL database (through Settings in CATS).
Please read the README before using the plugin.
NOTE: I've transcribed this over to the wiki at http://opencats.org/wiki/index.php?titl ... ion_module