I might be wrong, but I think that the tomcat server is strictly for serving up Java Server Pages (JSPs). To tie PHP into it, you'd also need to install regular apache and use a connector (like mod_jk2) to link them. Then compile PHP to use regular Apache.
Hugh Sparks has a pretty good writeup on the connection part at this link. Please note that the compile part on the mod_jk2 connector didn't work that well. The connector threw up continuous java scoreboard errors in my apache error_logs. Leaving the Apache source code available and linking into it during configuring saved me a lot of headaches. I also, linked directly to the Tomcat installation during the configure stage.
You don't really need to go into Cocoon, or mod_rewrite, or the sitemap.xmap or any of the extended xml stuff. Just get Tomcat tied into Apache properly and you'll be fine...