Here's what needs doing:
1 - Go here and download the 64 bit Linux installer (I'm on Centos 6 64bit)
2 - Make it executable and execute it, use the default values when asked or what you think is appropriate
3 - If you want to use a MySQL DB download this and extract from it mysql-connector-java-5.1.27-bin.jar, putting it in /opt/atlassian/confluence/confluence/WEB-INF/lib/ on the server
4 - Restart Confluence: service confluence restart
5 - Go to http://confluence.example.com:8090 and finish the setup, then go in Confluence Admin -> General Configuration and edit the Site Configuration Edit, updating Server Base Url to match the subdomain you want to use in the end, e.g. http://confluence.example.com or https://confluence.example.com if you want SSL. Save the settings.
6 - Enable proxing in Apache httpd; edit /etc/httpd/conf/httpd.conf and modify your virtualhost such that it looks like this:
<VirtualHost 220.127.116.11:443> DocumentRoot "/var/www/confluence" ServerName confluence.example.com SSLEngine on SSLCertificateFile /path/to/server.crt SSLCertificateKeyFile /path/to/server.key ProxyRequests Off ProxyPreserveHost On ProxyPass / http://127.0.0.1:8090/ ProxyPassReverse / http://127.0.0.1:8090/ </VirtualHost>7 - Edit /opt/atlassian/confluence/conf/server.xml and add this in the Connector's line: proxyName="confluence.example.com" proxyPort="443" scheme="https" so that it resembles this
8 - Restart both httpd and confluence services
9 - Go to https://confluence.example.com and enjoy!