If I'm not mistaken, the link from your last post tells you how to associate the file type with Notepad, so you don't have to modify the extension to open it?
Actually, if you use File/Open from Notepad, you can open literally any file (you need to change the file type at the bottom of the file browser dialogue).
Otherwise, a third party application like Notepad++, is a lot easier. You can drag/drop files onto its shortcut to open them, it doesn't care what extension they have. If it's essentially formatted as a text file, it will display everything.
