No this post isn't about using a txt-editor. 
In fact it's quite simple to get access to ALL files within a mpq file.
You need to start mpq2k in the dos-command mode or by using some executer programm.
However you do it, you'll have to enter the following thing:
"mp2k.exe l [mpq filename] > output.txt"
This will generate a txt file from every file within the mpq. You now have to use a txt editor or anythin similar to cut the txt down to the format used by mpqview, but thats pretty much it...
Hope i tell you something new with that one, else i would look rather silly, pointing out well-known facts, wouldn't i. 