I did the cheat with this game where I just played the last episode of each video. So by the time I was done the game I still needed to kill 30 dumb cops. So if you're like me, this might be a quick solution for you.
The level I used to kill the cops was in the deleted scenes of Slayaway Camp 2.5 - the 3rd episode (Ringing Rampage). There are 2 dumb cops in this episode and you can kill them pretty quick. Plus since it's a deleted scene you can just repeat it over and over till you get your 30.
The solution for this episode is:
Left (to the lower telephone)
Right
Up
Left (Kill the cop)
Left (to the upper telephone)
Down
Left (to the lower telephone)
Right
Down
Left
Up
Left
Down (kill the girl)
Left (kill the cop)
Left
Up
Right (to upper telephone)
Down (exit the level)