Ch340 provides the same exact functionality as an ftdi chip, however nefmoto is written using the ftdi api/drivers as ftdi chips carry an unique unchangeable id, etc., and nefmoto uses this. If nefmoto would be written with COM port support it should work.
The thing is, nef is now fully open source and does not even rely on the ID thing any more...
Again, all the source is on github, I would welcome anyone to take a look and issue pull requests.