Phone must be rooted.
Download "File Expert" Free from the market.
Choose "Phone Internal Storage"
Menu/More/Settings/File Explorer settings.
Check "Root Explorer".
Go back to "SD Card/Phone Internal Storage"
Menu/More/Mount//Mount As Read Write
Back/Phone Internal Storage.
Choose whichever Folder/File you wish.
Long Press File.
From List Choose "Permission".
Check "Read All" and "Write All" then "Apply".
Long press your chosen file again.
Choose "Open As/Text/" Choose a text editor from list. Change text to your liking. Menu/Save.
If asked to save on exit, save again.
We are done.