In the Show Text event command, you can hit F1 to show everything you can do with that. In this case what you need is typing:
CODE
\N[##]
## is where you put the desired actor ID. Now in the game, if character 1 is named Test and you write \N[1] or \N[001] it will in the game change into Test. If you want to see how it gets directly in the editor, you can in the "Show Text..." command hit F2 to get a preview.
Hope I'm clear enough.