Yes, I believe you can, players have added things like claws, but I do not know how, sorry. I do not know if you can change the shape of the character as a whole, as it has things like the running animations, and other things like that. To make things like whiskers, claws, etc, I am pretty sure you have to edit an existing mane file or something, so they take the place of a mane, or other parts you can add on to your character. Sorry if this is not much of a help XD