You can either load models from anywhere in you Toribash folder using
/obj load command (type /obj help to get more info on it) or make a custom item.dat folder that'd have the models you need enabled and put the obj files (named accordingly to their body parts) in that player's folder.
You can also check this tutorial for more info:
http://forum.toribash.com/showthread.php?t=492531
If you want to make your models publicly visible, you can either
submit them by sending to ES admins (or me) or use
Icky's shop. First option is free and you will even get TC if people buy your model from the shop but it takes time for us to release new stuff, second option is probably faster but you'd have to pay $30+ to get your model added.