Ok, playing around with it a bit...
First hurdle I ran into was that it didn't want to find the textures:
So I created the dir and copied all the textures the FBX exporter had created into it. But it still didn't seem to want to find the appropriate texture.
As said, my Unity skills are very lacking, so I might be missing something obvious. But maybe there should be a line in the readme about the texture dir.
Otherwise the pipeline seems smooth so far, from MHIimporter skel in MH to import. Maybe a .thumb file for the mhskel file would be a nice touch (it's just a 128x128 px PNG renamed to .thumb, to place alongside the mhskel in the rigs dir)
I'll try to figure out the posing later, but right now a customer is yelling at me because a mission critical server is unreachable. People become so neurotic from even such minor details...