Assumption:
clean fresh minimal installed RedHat or Centos (or any similar linux) registered and updated to the latest revisions:

This is a quick and dirty install for demo purpose. For the minimum of security please refer to http://doc.owncloud.org/server/5.0/admin_manual/installation.html

rhn_register      #with your details
yum -y update     #to get latest updates

make sure either dns is working or your hosts and IP are in the local /etc/hosts file

Time to start the clock:

Install the needed packages.

 yum -y install mysql-server httpd php php-mysql unzip wget php-json php-xml php-mbstring php-zip php-gd curl php-curl php-pdo

chkconfig httpd on; chkconfig mysqld on

#It might be a good idea to reboot the box here.
reboot

/etc/init.d/mysqld start
Initializing MySQL database:  
Installing MySQL system tables.. .  OK
Filling help tables...  OK
To start mysqld at boot time you have to copy  support-files/mysql.server
to the right place for your system
PLEASE REMEMBER TO SET A PASSWORD FOR THE MySQL root USER !
To do so, start the server, then issue the following commands:
/usr/bin/mysqladmin -u root password 'new-password'
/usr/bin/mysqladmin -u root -h wiki.whatever.ie password 'new-password'

Alternatively you can run: /usr/bin/mysql_secure_installation which
will also give you the option of removing the test databases and
anonymous user created by default.  
This is strongly recommended for production servers.
See the manual for more instructions. You can start the MySQL daemon
with: cd /usr ; /usr/bin/mysqld_safe & You can test the MySQL daemon
with mysql-test-run.pl cd /usr/mysql-test ; perl mysql-test-run.pl
Please report any problems with the /usr/bin/mysqlbug script!                      
[  OK  ] starting mysqld:

# /etc/init.d/httpd start

Install the mysql user and database.
I personally recommend using /usr/bin/mysql_secure_installation because its the cleanest way to get rid of all the garbage mysql brings with it.

see below…

# /usr/bin/mysql_secure_installation

  NOTE: RUNNING ALL PARTS OF THIS SCRIPT IS RECOMMENDED FOR ALL MySQL
  SERVERS IN PRODUCTION USE! PLEASE READ EACH STEP CAREFULLY! In order
  to log into MySQL to secure it, we'll need the current password
  for the root user. If you've just installed MySQL, and you haven't set
  the root password yet, the password will be blank,so you should just
  press enter here. Enter current password for root (enter for none):
  OK, successfully used password, moving on... Setting the root password
  ensures that nobody can log into the MySQL root user without the
  proper authorisation. You already have a root password set, so you
  can safely answer 'n'.
  Change the root password? [Y/n] y
  New password:
  Re-enter new password:
  Password updated successfully!
  Reloading privilege tables..

  ... Success!By default, a MySQL installation has an anonymous user, allowing anyone to log into MySQL without having to have a user account created for them. This is intended only for testing, and to make the installation go a bit smoother. You should remove them before moving into a production environment.

Remove anonymous users? [Y/n] y
... Success!

Normally, root should only be allowed to connect from 'localhost'. This ensures that someone cannot guess at the root password from the network.
Disallow root login remotely? [Y/n] y

... Success!

By default, MySQL comes with a database named 'test' that anyone can access. This is also intended only for testing, and should be removed before moving into a production environment.

Remove test database and access to it? [Y/n] y

 - Dropping test database...
 ... Success!
 - Removing privileges on test database...
 ... Success!
Reloading the privilege tables will ensure that all changes made so far will take effect immediately.

Reload privilege tables now? [Y/n] y
 ... Success!
Cleaning up...
All done! If you've completed all of the above steps, your MySQL installation should now be secure.
Thanks for using MySQL!

Now we create the database for wordpress

chkconfig mysqld on
echo 'CREATE DATABASE owncloud;' | mysql -p
echo "GRANT ALL PRIVILEGES ON owncloud.* TO 'owncloud'@'localhost' IDENTIFIED BY 'your_password';" | mysql -p
echo "FLUSH PRIVILEGES;" | mysql -p

Download Owncloud

cd /var/www/html
wget http://mirrors.owncloud.org/releases/owncloud-4.5.1.tar.bz2
#Updated to owncloud 5.0
wget http://download.owncloud.org/community/owncloud-5.0.7.tar.bz2

tar xvf owncloud-5.0.7.tar.bz2
rm -rf owncloud-5.0.7.tar.bz2

# owncloud needs these to be writable by the webserver

chown -R apache:apache owncloud

Go to http://yopur_ip_address/owncloud /

Follow the screen to add you Database details and your admin user and you’re done.

Oh yes … and  STOP THE CLOCK