Logically it is impossible to implement this but if it must be done for a certain group of people then here is a workaround for this.
1. Change the parameter rdisp/gui_auto_logout for a partcular application server and set it to 0 so that auto logout gets deactivated for that application server only.
2. Create a logon group and include this server only in that logon group and ask the users to use this group only for the logon or you can provide the information directly to them and say them to use the application server for the logon.
Auto logout is disabled for them now.
As I already mentioned it is not the exact soultion but just a wrokaround.
Let me know if more information is needed.
I hope it works for you.
Anand