Easy. Make the following class:
Perk 1: Lightweight + Flak Jacket
Perk 2: Fast Hands
Perk 3: Engineer
Lethals: C4 + C4
Tacticals: Blackhat + Blackhat
Wildcards: Perk 1 Greed + Danger Class
Next, go into Chaos Moshpit (Where Nuketown is) or go to Hardpoint if you don't have that. Run around the map the entire game killing people with the C4 when they're not close enough for you to knife them. Throw the C4 at them and kill them by double-tapping Square, not R2.
Protip: When throwing the C4 while the enemy is facing you or when under-fire, aim the C4 in the air in their direction while simutaneously moving either left or right so they miss bullets until the C4 blows up on them.
Play with 'ONLY' that class for 4 games in a row, and you will be Prestige Master by then or before then. You must also NOT go negative in any of those 4 games or you will have to start over. it is the final test; as a TRUE Master can kill more than he dies without using a gun.