If you are still running on a PostgreSQL version lower than 8.3 you might have to manually install PostgreSQL before installing the SURFids logging server.

Here's how this is done on an Debian Etch system:

apt-get -t etch-backports install postgresql-8.3
pg_dropcluster --stop 8.3 main
pg_upgradecluster -v 8.3 8.1 main
pg_dropcluster --stop 8.1 main

If the 8.1 cluster is not running while you are trying to do the pg_upgradecluster command, you will need to start it.

/etc/init.d/postgresql-8.1 start