ok insanes back and stronger. but if you want an easy way out just do a local co-op campaign and set the account wanting the achievment on insane and the other on casual(just have a guest singed in). then select any act/chapter but starting from the start will be easier. Just have the insane person hide back and let the casual do all the work.
some parts are easier if you sign the 2nd player out if you are doing by yourself like, act 3 chapter 1, act 3 chapter 3 or 4 well the driving act and act 5 chapter 5.
also you have to train the rook( Carmine) to get it.
not to mention if you want it properly just remember to use cover,blindfire in cover and don't rush as you get slowed down when you rodie run.