g1smd - 11:11 pm on May 22, 2012 (gmt 0)
PCRE allows for very compact and concise code that runs ultra efficiently. Anything you replace it with will usually be much less efficient.
That said, if I have a particular task that can be performed using PHP and the URL set is easy to discern, I'll internally rewrite those requests to a script for further handling.
Your particular problem first needs you to start by changing the links on the page to point to the URLs that you want users to see and use. URLs are defined in links. You'll then need an internal rewrite. This will connect requests generated after the link is clicked to the internal filepath that will handle that request. Separately you'll also need a redirect from the old URL format to the new format. Both of those things will each use a RewriteRule.