The first post in that thread has some necessary software to download to allow TTS apps to use text-to-speech on the eDGe.

The Word Player app only reads EPUB files.

It took me quite a while to find an app that can load and read TXT files. One such app is MultiReader. It's listed for $4.95 on SlideMe.org (http://www.slideme.org/application/multireader). I tested an older version I found elsewhere and it works. I believe this would be the app you're looking for.

One thing I noticed about Word Player and MultiReader is that they take about 30 seconds to load - don't hit the Back button, just wait for something to appear