Integration of JAAS Login Module for use with Form Based Authentication in Websphere 6.0

I am trying to figure out how to integrate a custom JAAS Login Module into Websphere for use with Form Based Authentication.  I am new to Websphere but have extensive experience with other Application Servers and the J2EE platform in general.  So this problem has me pretty frustrated.  

Maybe my expectations are off, but I am anticipating that I should be able to register my custom login module in such a way that when a user enters their credentials at the login page the authentication is handled by my login module instead of the default websphere user registry.  Note that in my web.xml file I am using FORM based authentication.

Before I describe my situation in detail I'll ask the questions that I think will get me a working solution.
How do you register a JAAS login module so that it will be called during the processing of the j_security_check servlet?

Background thusfar:
o  Global Security is Enabled
o  A JAAS Application Login Configuration called myrealm has been created and associated with my login module class (called TestJaasModule)
o  In the JAAS System Login Configuration I have inserted TestJaasModule into WEB_INBOUND and RMI_INBOUND in the first ordered spots.
o  I've gotten FORM based authentication to work against the default user registry (unfortunately this is not the security store that the production app will be using).

When I attempt to log into the application using credentials from the default user registry, it works.  However, if I use credentials from the security store serviced by my login module, then NO JOY!

Thanks kindly for your attention.

Here is web.xml

<web-app>
   <display-name>authtest</display-name>


   <session-config>
      <session-timeout>2</session-timeout>
   </session-config>


   <welcome-file-list>
      <welcome-file>/secure/welcome.jsp</welcome-file>
   </welcome-file-list>

   <security-constraint>
      <web-resource-collection>
         <web-resource-name>ReportCentral</web-resource-name>
         <description>
            Coarse access to use the report central application
         </description>
         <url-pattern>/secure/*</url-pattern>
         <http-method>GET</http-method>
         <http-method>POST</http-method>
      </web-resource-collection>
      <auth-constraint>
         <role-name>All Authenticated Users</role-name>
      </auth-constraint>
      <user-data-constraint>
         <transport-guarantee>NONE</transport-guarantee>
      </user-data-constraint>
   </security-constraint>


   <login-config>
      <auth-method>FORM</auth-method>
      <realm-name>myrealm</realm-name>
      <form-login-config>
         <form-login-page>/login.jsp</form-login-page>
         <form-error-page>/errorLogin.jsp</form-error-page>
      </form-login-config>
   </login-config>

   <security-role>
      <role-name>All Authenticated Users</role-name>
   </security-role>

</web-app>