If you use cutRsc then you can't modify the text of the dialog with ctrlSetText. Anyway I googled a bit and found another topic where a guy asked the same thing, and they told him it is not possible to do that. You might be able to do it in ArmA 2 with overlays but there isn't enough documentation about them so I just used hintSilent to display the message I want, it's the only text over there.