Existe uma maneira de carregar um HttpServlet personalizado no GAE? Fiz upload de um projeto que incluía um HttpServlet no pacote .server e o adicionei ao web.xml ...

<servlet>
   <servlet-name>testServlet</servlet-name>
   <servlet-class>gwtone.server.TestServlet</servlet-class>
</servlet>

<servlet-mapping>
   <servlet-name>testServlet</servlet-name>
   <url-pattern>/tester/greet</url-pattern>
</servlet-mapping>

Há mais alguma coisa que me falta ou não é possível?

--------EDITAR-------

algumas coisas que aparecem quando inicio meu servidor, que não estou acostumado a ver ...

Jan 22, 2012 4:23:44 AM com.google.apphosting.utils.jetty.JettyLogger info
INFO: Logging to JettyLogger(null) via com.google.apphosting.utils.jetty.JettyLogger
Jan 22, 2012 4:23:44 AM com.google.apphosting.utils.config.AppEngineWebXmlReader readAppEngineWebXml
INFO: Successfully processed E:\Program Files\eclipse-SDK-3.7.1-win32-x86_64\Workspace\gwtone\war\WEB-INF/appengine-web.xml
Jan 22, 2012 4:23:44 AM com.google.apphosting.utils.config.AbstractConfigXmlReader readConfigXml
INFO: Successfully processed E:\Program Files\eclipse-SDK-3.7.1-win32-x86_64\Workspace\gwtone\war\WEB-INF/web.xml
Jan 21, 2012 10:23:44 PM com.google.appengine.tools.development.DevAppServerImpl start
INFO: The server is running at http://localhost:8888/
Jan 21, 2012 10:23:44 PM com.google.appengine.tools.development.DevAppServerImpl start
INFO: The admin console is running at http://localhost:8888/_ah/admin

e aqui está o que mostra quando ele trava ..

WARNING: Error for /tester/greet
java.lang.VerifyError: Expecting a stackmap frame at branch target 14 in method gwtone.server.TestServlet.doGet(Ljavax/servlet/http/HttpServletRequest;Ljavax/servlet/http/HttpServletResponse;)V at offset 0
    at java.lang.Class.getDeclaredConstructors0(Native Method)
    at java.lang.Class.privateGetDeclaredConstructors(Unknown Source)
    at java.lang.Class.getConstructor0(Unknown Source)
    at java.lang.Class.newInstance0(Unknown Source)
    at java.lang.Class.newInstance(Unknown Source)
    at org.mortbay.jetty.servlet.Holder.newInstance(Holder.java:153)
    at org.mortbay.jetty.servlet.ServletHolder.initServlet(ServletHolder.java:428)
    at org.mortbay.jetty.servlet.ServletHolder.getServlet(ServletHolder.java:339)
    at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:487)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
    at com.google.appengine.tools.development.HeaderVerificationFilter.doFilter(HeaderVerificationFilter.java:35)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.appengine.api.blobstore.dev.ServeBlobFilter.doFilter(ServeBlobFilter.java:60)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.appengine.tools.development.StaticFileFilter.doFilter(StaticFileFilter.java:122)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.appengine.tools.development.BackendServersFilter.doFilter(BackendServersFilter.java:97)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
    at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
    at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
    at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
    at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
    at com.google.appengine.tools.development.DevAppEngineWebAppContext.handle(DevAppEngineWebAppContext.java:78)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at com.google.appengine.tools.development.JettyContainerService$ApiProxyHandler.handle(JettyContainerService.java:362)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at org.mortbay.jetty.Server.handle(Server.java:326)
    at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
    at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:923)
    at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:547)
    at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:212)
    at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
    at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:409)
    at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)

EDIT # 2

package gwtone.server;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class TestServlet extends HttpServlet {

public TestServlet(){}

@Override
public void doGet(HttpServletRequest req, HttpServletResponse resp) 
        throws ServletException, IOException {
    System.out.println("0");
    try {
        System.out.println("1");
        resp.getWriter().println("IT WORKED");
        resp.getWriter().flush();
        System.out.println("2");
    } catch (IOException e) {
        e.printStackTrace();
    }
    System.out.println("3");
}
}