I have no idea how it would work, but should not be very difficult. My concern is that 99% of players have no idea what compression is wog, what are creatures names, what is a def tool, what is a def, what is a lod. They would love to play with new models but the install process is too heavy for them.

Of course the mapmaker can provide a wog file with all names setup (we always did that), but in the case one just build some custom defs and the player should pick which creature to replace, build the wog file, pick name, he is helpless. What is easy for modders may become very complicate for players to implement. Should be automatized, if there is a slight chance it can. (not a request from me, but a suggestion, and I could help for listing them etc)
The creatures archive (HC) count so far more than 120 new models, but still no one picks them, for obvious reasons: they have no idea how to do it.