I don't think there is any way to make cutresources dynamic like that.
However, you can set the text of a DIALOG dynamically after the mission starts. Luckily for you (since you know how rscs work), dialogs are very similar to cutresources. The only visible difference in-game is that a cursor appears during dialogs, and the player can close it using the esc key. Search the ed depot for vectorboson's dialog tut to learn how to make them, and then search for razorwings' dialog maker for a handy program that will save you lots of hassle.