Proscaline has a great guide about the actual weapon so I will not cover that, instead my guide will focus on a quick way to get the 25 kills with the weapon.
I found an easy way to achieve this is to play
Conquest large on the map
downtown, for this method to work your team needs to have captured point
C. Once you have captured
C, use the T62 and guard the elevators, taking out any enemies that try to come up. Below is a game clip showing this technique.
Using this technique I got the 25 kills halfway through my second game on the map. I hope this helps