I agree with the comment above. If you feel the need to use Assassin and Overkill the obvious solution is to use the Specialist Strike Package. That is a much easier solution than reprogramming the game.

They're not going to change perk slots. Overkill is just one of those perks hardly anyone uses and thats too bad. Just set assassin as your 1st specialist perk so its only 2 kills away (1if you play Dom) and then try not to die. When I suffer from lag comp, the specialist bonus works wonders, and it's only an 8 kill streak.

I love using it on my sniper classes with slieght of hand, using either an SMG or AR for support if I have to give up my sniping spot and run around, it's nice to have a more reliable weapon for mid-range combat. Using Marksman as my 3rd perk with the Type-95 as my secondary, it's an awesome sniping class. Also use specialist, I notice most people are running specialist these days, a lot less kill streaks flying around.

assassin not over used...gtro. Its by far the most used 2nd tier perk.

I would love to be able to Overkill as a third perk, but I would rather see deathstreaks removed.