not very difficult to do: make a diagram of the current wiring of your guitar on a piece of paper (or ideally you would have downloaded the wiring from the official website)
then proceed one by one.
un screw both pickups so you get access to the wires more easily.
start with the neck pickup (IMO it is easier to do neck then bridge than the opposite)
identify the wires used by the pickup. unsolder them. remove the neck pickup.
take the new pickup install it in the guitar: solder the wires of the pickup exactly in the same way the previous pickup was setup in your guitar.
normally the color code should be the same in between the old and new pickup as they are both from DiMarzio...
once you have soldered these wires, screw the pickup in and proceed with the bridge pickup... same thing...
check this link out:
you will find the color codes for a series of brands.
with DM you have to solder the green to the ground.
i did it yesterday. i am still alive...
important: (and i hate to repeat myself)
GET THE WIRING DIAGRAM FROM THE OFFICIAL WEBSITE