When the PC power button* is pressed the well known Shutting Down message panel appears.
On this panel I need to remove the Cancel button, the Restart button and also the ShutDown button. I also need to change the countdown timer from 60 sec. to 10 sec.
So, the info panel shall be visible for 10 sec. then the PC shall be turned off (stand by) without any option.

At the same time, this Shutting Down message panel must be disabled at all (i.e. nothing happens) if the Ctrl+Alt+Del is pressed.

I do not want to change the Logoff message panel, available from System menu/Logoff.

Please advise!

*Note: I am using an industrial PC. There is not a regular Power On button like in case of workstations but there is PC_ON signal to control the operating system and motherboard stand by. I am not interested in such solutions modifying the power button with duct-tape or scissors...
I am interested in Linux configuration tricks, thx!
Red Hat Linux 6 (KDE 4.3.4)

I don't know much about modifying the shutdown dialog, but I can tell you where to configure the shortcuts.

You can find most shortcuts in System Settings -> Shortcuts and Gestures -> Global Keyboard Shortcuts. The Ctrl+Alt+Del shortcut can be found under The KDE Session Manager.
While there is an entry for a PowerOff actoin assigned to the Power Off button/signal under KDE Daemon in the keyboard shortcuts, I believe that is not what you are interested in. Instead you may be interested in System Settings -> Power Management -> Energy Saving where you should find a checkbox for Button events handling, with an associated dropdown for configuring what happens when the power button is pressed. Unfortunately I don't see any other options for dialogs besides the general log out dialog.

Now this is all in Ubuntu 14.04, KDE 4.14.13. Going back to KDE 4.3 there have been numerous significant changes to some of these settings and dialogs, so some of this may not even be available. That said, I'm fairly confident you should be able to configure the Ctrl+Alt+Del shortcut through a method similar to the one I described.