idle timeouts

[Kevin]

I need to implement idle timeouts, based on user input.  Our users
connect through a gateway host to access other machines.  Using the
"autolog" package on the gateway seems to work fine for shell sessions.
Keyboard input from users updates the utmp file on the gateway.
 
However, we have users who use port forwarding to run GUI apps such as
VNC.  User input from these apps don't appear to cause utmp updates.
 
Any suggestions?  There's a watchdog patch out there, but I'd rather not
resort to using patches.