Since JBuilder 3.5 comes with the JSWDK, which supports Servlet API 2.1/JSP 1.0, how can I get it to use Servlet API 2.2 / JSP 1.1?

You can follow this tutorial to setup JBuilder 3.5 to use and debug the Tomcat server, which is the reference implementation for Servlets 2.2 and JSP 1.1.