If you have installed emacs off of the Redhat 6.x CD, You already have perl mode for emacs installed. I use it all the time and it works great. What you want to do is turn on 'Syntax Highlighting', which in emacs is called 'font-lock-mode'. To turn on font lock mode globally select the Options from the help menu and check 'Global Font Lock' this will enable syntax highlighting for all emacs recognized programming languages (including perl).