Right now the process that ME-DEM guys use is fairly complex, mainly on the side of preparing the data outside of Outerra. Basically you are supposed to prepare the elevation data for your world in resolution around 100m. Even for relatively small continents it means large amounts of data to process, so you have to use tools that can manage such sizes.
The import is also hard-coded for ME data currently, I just hacked it to enable the ability to import their world. I need to create a generalized interface for the import. But if you (will) have the data, we can do something about it in a similar way.
I think Monks of ME-DEM wanted to create a tutorial for the process of how they produced the data, in order to look good in OT.