$ sudo port install postgresql82
--->  Fetching postgresql82
--->  Attempting to fetch postgresql-8.2.9.tar.bz2 from http://ftp8.us.postgresql.org/postgresql/source/v8.2.9
--->  Attempting to fetch postgresql-8.2.9.tar.bz2 from http://ftp9.us.postgresql.org/pub/mirrors/postgresql/source/v8.2.9
--->  Verifying checksum(s) for postgresql82
--->  Extracting postgresql82
--->  Configuring postgresql82
--->  Building postgresql82
--->  Staging postgresql82 into destroot
--->  Installing postgresql82 8.2.9_0
To use the postgresql server, install the postgresql82-server port
--->  Activating postgresql82 8.2.9_0
--->  Cleaning postgresql82
$ sudo port install postgresql82-server
Password:
--->  Fetching postgresql82-server
--->  Verifying checksum(s) for postgresql82-server
--->  Extracting postgresql82-server
--->  Configuring postgresql82-server
--->  Building postgresql82-server with target all
--->  Staging postgresql82-server into destroot
--->  Creating launchd control script
###########################################################
# A startup item has been generated that will aid in
# starting postgresql82-server with launchd. It is disabled
# by default. Execute the following command to start it,
# and to cause it to launch at startup:
#
# sudo launchctl load -w /Library/LaunchDaemons/org.macports.postgresql82-server.plist
###########################################################
--->  Installing postgresql82-server 8.2.9_0
To create a database instance, after install do
 sudo mkdir -p /opt/local/var/db/postgresql82/defaultdb
 sudo chown postgres:postgres /opt/local/var/db/postgresql82/defaultdb
 sudo su postgres -c '/opt/local/lib/postgresql82/bin/initdb -D /opt/local/var/db/postgresql82/defaultdb'
To tweak your DBMS, consider increasing kern.sysv.shmmax by adding an increased kern.sysv.shmmax .. to /etc/sysctl.conf
--->  Activating postgresql82-server 8.2.9_0
--->  Cleaning postgresql82-server

$ sudo mkdir -p /opt/local/var/db/postgresql82/defaultdb
$ sudo chown postgres:postgres /opt/local/var/db/postgresql82/defaultdb
$ sudo su postgres -c '/opt/local/lib/postgresql82/bin/initdb -D /opt/local/var/db/postgresql82/defaultdb'
Password:
The files belonging to this database system will be owned by user "postgres".
This user must also own the server process.
The database cluster will be initialized with locale ja_JP.UTF-8.
The default database encoding has accordingly been set to UTF8.
fixing permissions on existing directory /opt/local/var/db/postgresql82/defaultdb ... ok
creating subdirectories ... ok
selecting default max_connections ... 30
selecting default shared_buffers/max_fsm_pages ... 2400kB/20000
creating configuration files ... ok
creating template1 database in /opt/local/var/db/postgresql82/defaultdb/base/1 ... ok
initializing pg_authid ... ok
initializing dependencies ... ok
creating system views ... ok
loading system objects' descriptions ... ok
creating conversions ... ok
setting privileges on built-in objects ... ok
creating information schema ... ok
vacuuming database template1 ... ok
copying template1 to template0 ... ok
copying template1 to postgres ... ok
WARNING: enabling "trust" authentication for local connections
You can change this by editing pg_hba.conf or using the -A option the
next time you run initdb.
Success. You can now start the database server using:
    /opt/local/lib/postgresql82/bin/postgres -D /opt/local/var/db/postgresql82/defaultdb
or
    /opt/local/lib/postgresql82/bin/pg_ctl -D /opt/local/var/db/postgresql82/defaultdb -l logfile start