Increase timeout in BusinessObjects 4.0?

How do I increase the timeout period of both the CMC and BI Lauchpad web browser sessions?

I have checked the web.xml file in <install-directory>\SAP BusinessObjects\Tomcat6\webapps\BOE\WEB-INF...

<session-config>

     <session-timeout>20</session-timeout>

</session-config>

My sessions are definitely not lasting 20 minutes.  I will do some timing later today to be sure.  Are there other settings I am missing that need to be checked?

We are on BusinessObjects 4.0 SP04 Patch 5.

Thanks,

Noel