I executed this demo on an Oracle Linux 5.7 64-bit system.
To achieve this, you'll have to execute these steps:
(1) Install WLS + configure domain (admin server + managed servers + cluster) + install the necessary rpm's + define the correct properties in the file "/etc/hosts".
(2) Download the latest Apache installer for your OS (http://httpd.apache.org/download.cgi).
(3) Copy the file to the desired directory and unzip the file
(4) Configure Apache
(5) Make Apache
(6) Make Install Apache
(7) Copy the mod_wl_22.so file to the apache directory structure
(8) Open the file /opt/apache/conf/httpd.conf and edit some general parameters (like ServerName, User, Group etc)
(9) In the same file, load the mod_wl_22.so into Apache and define the properties of your WLS domain
(10) Log in as root to start or shut down Apache
P.S.: On Oracle Linux you can of course install Apache through yum.