Making the build is fairly easy, as all you need are the three joker skills aced, which is a total of 22 skill points to get to them, and to ace them.
These three skills aced are required to make Jokers viable on higher difficulties, like One Down and Death Wish, as they will be able to soak up a lot of damage.
If you're going to go on Death Wish or One Down, you're also gonna want to pick up inspire, so your Mastermind tree will look something like this:

Hostage Taker, while not required, is highly suggested as it provides health regen while your jokers are up.
Moving on, we go to Ghost and get enough points to get Low Blow and Sneaky Bastard basic, as well as standard dodge skills.

While this is not required for Death Wish and below, if you plan to go on One Down you're also gonna need to pick up the skills you see in my Fugitive tree here.

Nine Lives aced basically turns One Down into Two Down, and it greatly reduces medical supply usage, Swan Song is used for getting into cover so you can be revived, and Feign Death is useful due to the spawnrates on One Down.
This build leaves you with 21 Skill Points that you can do whatever you want with, so if you want to make the build a silent killer build, or put points into shotguns, you are free to do so.

For Perk Decks, your choice is primarily up to personal taste, however there are four perk decks you should use depending on playstyle and difficulty.
If you feel you have good enough dodge, you should use Crew Chief, primarily for the Marathon Man and Hostage Situation perks.

However, considering the fairly low dodge you will be getting without Rogue, I suggest you use Rogue for serious play.

If, for whatever reason, you do not like having movement speed, and prefer armor, you should use Kingpin, from the Scarface Character Pack.

If you don't have the Scarface Character Pack, use Armorer.

If you're playing with the Dodge setup, you're generally gonna want as much concealment as possible (Low Blow and SB basic effects hit their max at five concealment), however there is one weapon you should always use in this build; the Electrical Brass Knuckles.

This weapon is EXTREMELY useful in getting jokers, as it has the same effect on them as tasers do on players, and it stuns them, meaning you get time to spam F to try and get them to surrender and get a Joker. This significantly reduces the risk of going down on higher difficulties trying to get a Joker, since you cannot get shot back by your victim.

At first glance, you might think "oh, all jokers are the same, why would this be important" and that is where you are completely wrong. Jokers have varying skills depending on the original cop you converted them from, so for example, a Chimano Street Cop converted into a Joker has trash for health, even fully upgraded, but it has absolutely ridiculous damage output because of Overkill's balance. Generally, you're going to want to convert the heavy cops (identified by their additional armor) into Jokers, as they have more health and on higher difficulties, unique properties.

• Yellow Swat
  
  Yellow Swat are the earliest heavy unit in the game. They very rarely spawn on Normal, and are a common sight on Hard. Outside of these two difficulties, they only spawn in scripted events.
  
  
• Maximum Force Responder
  
  Maximum Force Responders (more commonly referred to as Tans) are the first heavy swat with a special property, and in the case of MFRs, this is in their tan vest, which blocks all shots that hit the front of the chest, making them the best possible Jokers in the difficulties they spawn in outside of scripted events.
  They spawn rarely on Very Hard, frequently on Overkill, and are the most common enemy on Mayhem. Retextured versions of the MFR spawn on Death Wish and have a digital urban camo applied to them.
  
  
• Heavy ZEAL Swats
  
  Heavy ZEAL Swats are the toughest non-special enemy in the game. Functionally, they are identical to the MFR in that they have a vest that blocks all shots. This is EXTREMELY useful on One Down as standard ZEAL Swats will get chewed up very, VERY quickly.
  Heavy ZEAL Swats only spawn on One Down.

This is just an extra bit for stuff (read: mods) that makes Jokers even better.
Keepers[modworkshop.net]: Grants finer degrees of control over both regular AI bots and Jokers, such as telling them to stay in cover so you can perform an objective.
Iter[https//mhttps]: Makes the AI pathing not retarded