apt-get install slapd ldaputils libldap libldap2-dev openssl ldapscripts libpam-ldap ldap-client

During installation, you will be asked to configure ldap-auth-config. For this example, and for general compsoc website development, the following are the recommended answers:

ldap server name: ldapi://localhost/
Distinguished name of the search base: dc=compsoc,dc=nuigalway,dc=ie
LDAP version to use: 3
Make local root database admin: yes
Does the LDAP database require login: no
LDAP account for root: cn=admin,dc=compsoc,dc=nuigalway,dc=ie
LDAP root account password: password

emerge openldap pam_ldap nss_ldap

Next step is to modify the ldap server config file /etc/slapd.conf

Ubuntu https://help.ubuntu.com/community/OpenLDAPServer
Gentoo http://www.gentoo.org/doc/en/ldap-howto.xml
TLDP http://www.tldp.org/HOWTO/html_single/LDAP-HOWTO/
Migration http://quark.humbug.org.au/publications/ldap/system_auth/sage-au/system_auth.html
Migration Scripts http://www.padl.com/OSS/MigrationTools.html