Yeah Notre Dame fans during the games are there typically to cheer for the Irish, not so much heckle the other team. Our fanbase isn't like OSU or Michigan, those are the type of games you will receive some verbal and possible physical interaction during and or after the game, atleast the games I've been to. I think you will be good to go even if you were to wear a BYU jersey. You may get some unfriendly looks or a 'boo' here and there, but I assume you're expecting that.
Have fun and enjoy that great campus, make sure to get there early enough so you can look around.
Go Irish