Hi Dmitri,
Thanks for your reply. It might be an option but it has few disadvantages like - by default user is notified 5 minutes before task execution which is not enough. It can be temporary changed by changing value in registry for "Notification Countdown Period (mins)" under "HKEY_LOCAL_MACHINE\SOFTWARE\Altiris\Altiris Agent" but it gets overwritten when agent restarts or new policy arrives. But maybe there is somewhere some other way to achieve it.
Another minor downside is that when the pop-up appears on the top user press Enter and easily trigger the SW installation by accident.
It also seems to me like this Prompt user before running option needs to be specified for each SW within the policy which is not a big deal but it might be annoying for the user.
So for me more suitable would be to use User interaction within the policy but do not give user possibility to disable it.