Hibernatus has recently written a nice utility that let you dump and insert the text from/into scumm games, even if the lenght of the text varies.
you can grab the latest version here:
http://hibernatus34.free.fr/scumm/)
So far it seems to work well, but please note that it hasn't been widely tested yet and that some bugs may be left out.
I've been messing a bit with it, and I've been able to insert special chars in indy3 256...
http://www.abandonware-forums.org/attachment.php?s=&postid=219267)
Since some characters are not supported by the current game files (the с, for example doesn't exist in indy3 256), Hibernatus may also create a font editor.
options:
-1: The Secret of Monkey Island (CD)
-2: Monkey Island 2: LeChuck's Revenge (CD)
-3: Indiana Jones and the Last Crusade (256 colours)
-4: Indiana Jones and the Fate of Atlantis (CD)
-l: Loom (CD)
-z: Zak Mc Kracken (FM Towns)
-L: Loom (16 colours) for exporting only (quick and dirty beta function)
-I: Indy3 (16 colours) for exporting only (quick and dirty beta function)
-i: Input. Update the game files.
-o: Output. Extract the text from the game files.
-f <path>: Input/Output file. (default: ./text.dat)
-g <path>: Game file. (default: ./00.LFL or ./MONKEY.000 etc.)
-c: Don't convert characters to the "occidental" set of Windows.
-b: Don't leave backup copies of the game files.
-h: Line header.
-v: Verbose.
-V: More verbose.
-w: Windows newline format (\r\n).
examples:
scummtr -2ogf MI2/MONKEY2.000 monkey2.txt
scummtr -if indy3_fr.txt -3bVc -g I3/00.LFL
BTW, he used ScummVM as a documentaion source, there is nothig directly borrowed / copied. No GPL violation :)