Hi Peter,
You could turn off Session Deletion _completely_ by overriding the _GarbageCollector method in the WebServer procedure.
ie in WebServer, in _GarbageCollector method.
Before the parent call;
RETURNBUT - and it's a rather big BUT - I would do this with some caution. Never means Never, which means that eventually the server will consume memory until it is all gone. Each time a client machine reboots they will get a new session, so even if you had a limited number of client machines you will have infinite sessions.
IF you want a "really long" timeout, that's possible - if so ask that as a new question
Cheers
Bruce