For the skeletal meshes, I think I could export/import .mclmdl format to MD5, because this is the same principle.
However, the MD5 format uses a different way to animate models : for each animation, the editor saves it in a file, with vertex coordinates for each frame (24 by seconds generally). I knew this concept when I began to animate my models, and I found them pretty heavy for really simple animations, as Minecraft's ones.
So I've made a different one : This is based on periodic or static animations, with a few parameters (7), I can make simple animations, like those of Minecraft.
The advantages of this method are the model's size (zombie file is 13 Ko, with every vertex and 3 animations), the facility to make animations in the editor, and it's doesn't use much ressources in game.
The inconvenients are the enability to make other shape than cubes, and you can't make very complex animations with it.
So I can propose to you to make a ".mclmdl" loader directly in Terasology, because I couldn't export to MD5 format without losing all the advantages my editor offers. If you want to keep MD5 format, Blender or any other "bigger" editor are more adaptated than mine