I suggest you download the
2.49b stable version of Blender for add-on creation. Be sure to get the zip version, since it comes with some extra exporters and importers.
Also, you should get the .dts exporter. I use an older version of it, but the newest version should work too, which can be found
here.
To install the exporter, you need to unzip it to /*rootBlenderFolder*/.blender/scripts/
the .blender folder is hidden by default in windows, so you will need to change the view options in the explorer window to show all files and folders if you haven't already.
Just keep in mind that over half the buttons and features in Blender aren't needed for creating models for Blockland. I've been using Blender for a year or two now, and there are still some features and buttons that I've never used. :P
Happy Blending!