Changing sound files for specific league champions.

Hello

Recently I've been thinking that it would be hillarious to replace the sound of rengar jumping (right click from brush or ult) to a kitty's meow, however, I am unsure whether this is allowed rule-wise, and if its even possible after they changed how the file structure is (as vLoc does not work anymore)

Coould anyone give me some insight into whether this is allowed, and even possible?