I suggested something similar.
And there wont be any coding to be done, hopefully.
Because in Standard Half-Life Deathmatch. You can add custom
models. Of course, the other person wouldn't see it because
he will need to have the same folder/model. Or else he will just
see the player.mdl which is Gordon Freeman, in ESF its Gokou.
I also suggested there should be something like AHL armory.
To apply custom Attacks to your new player model. This would
also save up the time of the ESF team not wanting to model new
characters or have characters from another saga/movie.