Models Modding

[facosa_rap]

Hello there, im new to this and im interested in creating some models mods, like those on Left4Dead, replacing original characters (Not only bio and voice, but ingame appeareance as well) with random stuff like clowns, anime characters, hitler, etc.
Could you recomend me some programs and methods?

[Dmitriy]

http://steamcommunity.com/sharedfiles/filedetails/?id=973987851

[facosa_rap]

Nice <2+1