I am not sure if I understood your question correctly but if you simply go to the file
$CATALINA_HOME/webapps/ROOT/index.jsp and change its contents.
Access it using http://localhost:8080/index.jsp , it does show up the updated JSP.
I think you are accessing the root web-application using http://localhost:8080 and that keeps serving you the Apache default welcome page. That is being served by the index.html in the web-application.
You can delete index.html, so that you would be able to see the index.jsp as the default page that is served.
There is also a WELCOME FILE LIST construct available in the web.xml using which you can specify the order in which index page can be found.
With regards to forcing recompilation you can check the attributes defined for web.xml here -
http://localhost:8080/docs/jasper-howto.html ( These are reference to the local documentation that is installed when you setup tomcat locally.
Hope this helps.
subject: How can I edit and force a recompile of default Tomcat5 index.jsp?