Why can't you just use an ordinary text box?
If you want to make a nicer looking box to type in, just put the actual textbox off-screen and force set-focus to the textbox when you want the player to type in the name. Then create a nicer looking box on the screen for players to see - but it doesn't really do the hard work.
You can reflect whatever is in the textbox just using some sprite fonts or whatever for your "visible to the player" version of the textbox.
I hope this makes sense?