I do not fully understand your question. Especially not which files you want to parse?
If you want extensions other than ".jsp" to be handled by the JspServlet you simply have to change the servlet-mapping element of the default-web.xml for the JspServlet. This is the Servlet that takes care of JSPs, triggers their transformation to Servlets and so on. The default-web.xml can be found in the config-directory of your domain. E.g. GF_HOME/domains/domain1/config/default-web.xml
Now .htaccess makes me wonder even more what your question is about. Isn't .htaccess only about access restrictions? So what has it to do with parsing files? Maybe you can explain a bit more which files you want to parse, what role access restrictions shall play and how any other configuration might help by that.
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